Réponse :
a) (4x-1)(4x + 1) = (a-b)(a+b) = a²-b² = (4x)²-1² =16x²-1
b) (3 + 2x)²= (a+b)²= a²+2ab+b²
9+12x+4x²= 4x²+12x+9
c) 3a(5-2a)=
3a*5 + 3a*(-2)=
15a-6a²= -6a²+15a
d) (y + 2) (5y - 3) =
y*5y + y*-3 + 2*5y + 2*-3=
5y²-3y+10y-6=
5y²+7y-6
1) Application : calculer.
a) (1-√2)² = (a-b)²= a²-2ab+b²
1²-2(1*√2)+(√2)²=
1-2√2+2 = -2√2+3
b) (√3-2)(√3+ 2) =(a-b)(a+b) = a²-b²
(√3)²-2²=3-4=-1
Explications étape par étape :
