Question

find the limits of real value of x so that the expression 5x^2+6x-8 is non negative

Answer 1

Here's your answer...

$= 5 {x}^{2} + 6x - 8 \\ = 5 {x}^{2} + 10x - 4x - 8 \\ = 5x(x + 2) - 4(x + 2) \\ = (5x - 4)(x + 2)$

The limits are x+2 and 5x...