Question

If 4x^2 - 100 = 0, the roots of the equation are

(1) -25 and 25 (3) -5 and 5
(2) -25, only (4) -5, only

Answer 1

`4x^2-100=0 \ \ \ \ \ \ |+100 \\ 4x^2=100 \ \ \ \ \ \ \ \ \ \ \ |/ 4 \\ x^2=25 \\ x=\pm √(25) \\ x=\pm 5 \\ x=-5 \hbox{ or } x=5`

The answer is (3) -5 and 5.