Question

write a quadratic equation whose roots are -1 and 2 and whose leading coefficient is 2

Answer 1

because the roots are -1 and 2
so
(x+1)(x-2)=0
and multiply one of them by 2 because its a leading coefficient. lets say the first one
2(x+1)(x-2)=0
and distribute
(2x+2)(x-2)=0
FOIL and combine like terms to find your equation