Question

What are the solutions of the equation (x + 2)2 – 2(x + 2) – 15 = 0? Use u substitution to solve.

Answer 1

Answer:B. x=-5 and x=3

Explanation:

just took the test.

Answer 2

Explanation:

hello :

(x + 2)2 – 2(x + 2) – 15 = 0

let : t= x+2

t²-2t-15 =0

(t-5)(t+3)=0

t-5=0 or t+3=0

t=5 or t=-3

but : t =x+2

if : t=5 x+2 =5 so : x=3

if : t= -3 x+2 = -3 so : x= -5

conclusion two solutions : 3 , -5