Question

Bài 1.     Giải các phương trình sau
(x+1)(x+9)=(x+3)(x+5)
(x-1)^3 -x(x+1)^2=5x(2-x)-11(x+2)

Answer 1

Bài 1:

(x+1)(x+9)=(x+3)(x+5)

⇔x²+10x+9=x²+8x+15

⇔2x-6=0

⇔x=3

(x-1)³-x(x+1)²=5x(2-x)-11(x+2)

⇔x³-3x²+3x-1-x³-2x²-x=10x-5x²-11x-22

⇔-5x²+2x-1=-5x²-x-22

⇔3x+21=0

⇔x=-7