pouvez vous m'aider svp❤

bonjour,
a développer
f(x)=4(x-1)²-9
f(x)=4(x²-2x+1)-9
f(x)=4x²-8x+4-9
f(x)=4x²-8x-5

b factoriser
4(x-1)²= 4(x²-2x+1)=4x²-8x+4
4x²-8x+4=(2x-2)²
f(x)=4(x-1)²-9
f(x)=(2x-2)²-9
f(x)=(2x-2)-3²
f(x)
((2x-2)+3))((2x-2)-3))
f(x)=(2x-2+3)(2x-2-3)
f(x)=(2x+1)(2x-5)

f(x)=0
(2x+1)(2x-5)=0
2x+1=0 2x=-1
x=-1/2 x=-0.5
2x-5=0 2x=5  x=5/2  x=2.5

f(x)=-5
4x²-8x-5=-5
4x²-8x=-5+5
4x²-8x=0
4x(x-2)=0
4x=0 x=0
x-2=0  x=2

f(x)=4x²
4x²-8x-5=4x²
4x²-4x²-8x-5=0
-8x-5=0
8x=-5
x=-5/8  x=-0.65