feat(lessons): add lessons from client db
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135
src/components/lessons/RadicalSolutionWidget.tsx
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135
src/components/lessons/RadicalSolutionWidget.tsx
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import React, { useState } from 'react';
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const RadicalSolutionWidget: React.FC = () => {
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// Equation: sqrt(x) = x - k
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const [k, setK] = useState(2);
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// Intersection logic
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// x = (x-k)^2 => x = x^2 - 2kx + k^2 => x^2 - (2k+1)x + k^2 = 0
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// Roots via quadratic formula
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const a = 1;
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const b = -(2*k + 1);
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const c = k*k;
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const disc = b*b - 4*a*c;
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let solutions: number[] = [];
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if (disc >= 0) {
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const x1 = (-b + Math.sqrt(disc)) / (2*a);
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const x2 = (-b - Math.sqrt(disc)) / (2*a);
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solutions = [x1, x2].filter(val => val >= 0); // Domain x>=0
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}
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// Check validity against original equation sqrt(x) = x - k
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const validSolutions = solutions.filter(x => Math.abs(Math.sqrt(x) - (x - k)) < 0.01);
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const extraneousSolutions = solutions.filter(x => Math.abs(Math.sqrt(x) - (x - k)) >= 0.01);
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// Vis
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const width = 300;
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const height = 300;
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const range = 10;
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const scale = 25;
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const toPx = (v: number, isY = false) => isY ? height - v * scale - 20 : v * scale + 20;
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const pathSqrt = () => {
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let d = "";
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for(let x=0; x<=range; x+=0.1) {
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d += d ? ` L ${toPx(x)} ${toPx(Math.sqrt(x), true)}` : `M ${toPx(x)} ${toPx(Math.sqrt(x), true)}`;
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}
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return d;
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};
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const pathLine = () => {
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// y = x - k
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const x1 = 0; const y1 = -k;
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const x2 = range; const y2 = range - k;
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return `M ${toPx(x1)} ${toPx(y1, true)} L ${toPx(x2)} ${toPx(y2, true)}`;
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};
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// Phantom parabola path (x = y^2) - representing the squared equation
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// This includes y = -sqrt(x)
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const pathPhantom = () => {
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let d = "";
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for(let x=0; x<=range; x+=0.1) {
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d += d ? ` L ${toPx(x)} ${toPx(-Math.sqrt(x), true)}` : `M ${toPx(x)} ${toPx(-Math.sqrt(x), true)}`;
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}
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return d;
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};
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return (
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<div className="bg-white p-6 rounded-xl shadow-lg border border-slate-200">
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<div className="flex flex-col md:flex-row gap-8">
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<div className="w-full md:w-1/3 space-y-6">
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<div className="bg-slate-50 p-4 rounded-xl border border-slate-200">
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<div className="text-xs font-bold text-slate-400 uppercase mb-2">Equation</div>
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<div className="font-mono text-lg font-bold text-slate-800">
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√x = x - {k}
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</div>
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</div>
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<div>
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<label className="text-xs font-bold text-slate-500 uppercase">Shift Line (k) = {k}</label>
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<input type="range" min="0" max="6" step="0.5" value={k} onChange={e => setK(parseFloat(e.target.value))} className="w-full h-2 bg-slate-200 rounded-lg accent-indigo-600 mt-2"/>
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</div>
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<div className="space-y-3">
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<div className="p-3 bg-emerald-50 rounded border border-emerald-100">
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<div className="text-xs font-bold text-emerald-700 uppercase mb-1">Valid Solutions</div>
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<div className="font-mono text-sm font-bold text-emerald-900">
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{validSolutions.length > 0 ? validSolutions.map(n => `x = ${n.toFixed(2)}`).join(', ') : "None"}
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</div>
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</div>
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<div className="p-3 bg-rose-50 rounded border border-rose-100">
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<div className="text-xs font-bold text-rose-700 uppercase mb-1">Extraneous Solutions</div>
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<div className="font-mono text-sm font-bold text-rose-900">
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{extraneousSolutions.length > 0 ? extraneousSolutions.map(n => `x = ${n.toFixed(2)}`).join(', ') : "None"}
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</div>
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</div>
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</div>
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<p className="text-xs text-slate-400 leading-relaxed">
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The <span className="text-rose-400 font-bold">extraneous</span> solution is a real intersection for the <em>squared</em> equation (the phantom curve), but not for the original radical.
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</p>
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</div>
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<div className="flex-1 flex justify-center">
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<div className="relative w-[300px] h-[300px] bg-white border border-slate-200 rounded-xl overflow-hidden">
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<svg width="100%" height="100%" viewBox="0 0 300 300">
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{/* Grid */}
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<defs>
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<pattern id="grid-rad" width="25" height="25" patternUnits="userSpaceOnUse">
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<path d="M 25 0 L 0 0 0 25" fill="none" stroke="#f8fafc" strokeWidth="1"/>
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</pattern>
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</defs>
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<rect width="100%" height="100%" fill="url(#grid-rad)" />
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{/* Axes */}
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<line x1="20" y1="0" x2="20" y2="300" stroke="#cbd5e1" strokeWidth="2" />
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<line x1="0" y1={toPx(0, true)} x2="300" y2={toPx(0, true)} stroke="#cbd5e1" strokeWidth="2" />
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{/* Phantom -sqrt(x) */}
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<path d={pathPhantom()} fill="none" stroke="#cbd5e1" strokeWidth="2" strokeDasharray="4,4" />
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{/* Real sqrt(x) */}
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<path d={pathSqrt()} fill="none" stroke="#4f46e5" strokeWidth="3" />
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{/* Line x-k */}
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<path d={pathLine()} fill="none" stroke="#64748b" strokeWidth="2" />
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{/* Points */}
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{validSolutions.map(x => (
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<circle key={`v-${x}`} cx={toPx(x)} cy={toPx(Math.sqrt(x), true)} r="5" fill="#10b981" stroke="white" strokeWidth="2" />
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))}
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{extraneousSolutions.map(x => (
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<circle key={`e-${x}`} cx={toPx(x)} cy={toPx(-(Math.sqrt(x)), true)} r="5" fill="#f43f5e" stroke="white" strokeWidth="2" />
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))}
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</svg>
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<div className="absolute top-2 right-2 text-xs font-bold text-indigo-600">y = √x</div>
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<div className="absolute bottom-10 right-2 text-xs font-bold text-slate-500">y = x - {k}</div>
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</div>
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</div>
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</div>
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</div>
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);
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};
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export default RadicalSolutionWidget;
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