enfaite c : (X+5)©=25 ©=au carré svp

(x+5)² = 25
<=> x*x + 2*x*5 + 5*5 = 25
<=> x² + 10x + 25 = 25
<=> x² + 10x = 25 - 25
<=> x² + 10x = 0
<=> x(x+10) = 0 (J'ai factoriser)
<=> x = 0 OU x+10=0
<=> x = 0 OU x = -10

S={0; -10}