Sagot :
a. x(2x-5)=2(2x-5)
2x²-5x = 2x²-10
2x²-2x²-5x=-10
-5x=-10
5x=10
x=10/5=2
b. (5x+2)(2x-3)=4x²-12x+9
10x²-15x+4x-6=4x²-12x+9
10x²-4x²-15x+12x-6-9=0
6x²-3x-15=0
c. 5x²=8x(x+1)
5x²=8x²+8x
5x²-8x²-8x=0
-3x²-8x=0
d. (2x+1)²=9
4x²+2x+1=9
4x²+2x-8=0
e. (4x+7)² = (x-2)²
16x²+28x+49=x²-2x-4
16x²-x²+28x+2x+49-4=0
15x²+30x+45=0