Bonjour,
a.7x²+28x-35
7(x²+4x-5)
7(x²+5x-x-5)
7(x*(x+5)-(x+5))
=7(x-1)*(x+5)
b.-2x²-2x-1/2
-(2x²+2x+1/2)
-(√2x+1/√2)²
=-(√2x+√2/2)²
c.-5+8x+4x²
4x²+8x-5
4x²+10x-2x-5
2x*(2x+5)-(2x+5)
=(2x-1)*(2x+5)
d.8t²-18
2(4t²-9)
=2(2t-3)*(2t+3)
