Question

Write a quadratic equation in standard form that has roots at
-4/5 and 3

Answer 1

5x²-11x-12=0

Explanation:

1) the rule: if quadratic equation is ax²+bx+c=0 and x₁; x₂ are its roots, then x₁+x₂= -b and x₁*x₂=c. The value of 'a' can be calculated by 'b' and 'c'.

2) according to the rule above it is possible to make up the required equation:

b= -(-4/5+3)= -(-0.8+3)= -2.2 and c=(-4/5)*3= -2.4.

x²-2.2x-2.4=0; ⇔ 5x²-11x-12=0.