(x + 1)(x + 2) = (2 - x)(x + 2)
<=> x2 + 2x + x + 2 = 4 - x2
<=> x2 + 3x + 2 = 4 - x2
<=> x2 + 3x + 2 - 4 + x2 = 0
<=> 2x2 + 3x - 2 = 0
<=> 2x2 + 4x - x - 2 = 0
<=> 2x(x + 2) - (x + 2) = 0
<=> (x + 2)(2x - 1) = 0
<=> x + 2 = 0 hoặc 2x - 1 = 0
<=> x = -2 hoặc x = 1/2
còn bài 2 nữa bạn
ư ư :<
a) 2(m + 3/5) - (m + 13/5) = 5
<=> 2m + 6/5 - m - 13/5 = 5
<=> m - 7/5 = 5
<=> m = 5 + 7/5
<=> m = 32/5
b) \(\frac{2\left(3m+1\right)+1}{5}-\frac{2\left(3m-1\right)}{5}+\frac{3m+1}{10}=5\)
<=> 15(2m + 1) - 8(3m - 1) + 3(3m + 2) = 100
<=> 30m + 15 - 24m + 1 + 9m + 6 = 100
<=> 12m + 27 = 100
<=> 12m = 100 - 27
<=> 12m = 73
<=> m = 73/12