WAEC 2020 · Paper 1 · Q15

Find the quadratic equation whose roots are $\frac12$ and $-\frac13$ .

Worked solution (try it first)

Roots $\frac12$ and $-\frac13$ give the factors $(2x - 1)$ and $(3x + 1)$ , cleared of fractions.
Expand: $(2x - 1)(3x + 1) = 6x^2 + 2x - 3x - 1$
$= 6x^2 - x - 1$ .
So the equation is $6x^2 - x - 1 = 0$ , option D.