Đáp án:
11x+42-2x=100-9x-22 2x-(3-5x)=4(x+3) 11x-2x+9x =100-22-42 2x-3+5x =4x+12
18x =36 2x+5x-4x=12+3
x =36:18 3x =15
x =2 x =15:3=5
x(x+2)=x(x+3) 2(x-3)+5x(x-1)=5x²
x²+2x =x²+3x 2x-6+5x²-5x =5x²
x²-x²+2x-3x=0 5x²-5x²+2x-5x=6
-x =0 -3x =6
x =0 x =6:-3=-2