Question

It is known that x=7 is a root of the equation ax^2 + bx + 2= 0, where a<0. Solve the inequality ax²4 +bx^2 + 2>0.

Answer 1

2/(7a) < x < 7

Explanation:

The product of roots of ax² +bx +c is c/a. In this case, that means the second root of the equation is ...

... 2/(7a)

Since a < 0, the parabola opens downward and 2/(7a) < 0. The quadratic function will be positive between the two roots, on the interval ...

... 2/(7a) < x < 7