JAMB 2003 · UME · Q14

The graphs of $y = x^2 + 4$ and a straight line $PQ$ are drawn to solve the equation $x^2 - 3x + 2 = 0$ . What is the equation of $PQ$ ?

Worked solution (try it first)

Rearrange the equation to have $x^2$ alone: $x^2 = 3x - 2$ .
Add 4 to both sides so the left side matches the curve: $x^2 + 4 = 3x + 2$ .
So the curve $y = x^2 + 4$ meets the line $y = 3x + 2$ at the roots.
$PQ$ is $y = 3x + 2$ , option A.

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