Đáp án:
1) 5.(4 - x) - 7.(-x + 2) = 4 - 9 + 3
\(\Leftrightarrow 20 - 5x + 7x - 14 =-2 \)
\(\Leftrightarrow 2x=-8\)
\(\Leftrightarrow x=-4\)
2) -3.(x - 5) + 6.(x + 2) = 9
\(\Leftrightarrow -3x + 15 + 6x + 12 = 9\)
\(\Leftrightarrow 3x = -18\)
\(\Leftrightarrow x=-6\)
3) 4.x - 5.(-3 + x) = 7
\(\Leftrightarrow 4x + 15 - 5x = 7\)
\(\Leftrightarrow -x = -8\)
\(\Leftrightarrow x=8\)
4) 5.(x - 3) - 2.(x + 6) = 9
\(\Leftrightarrow 5x-15-2x-12=9\)
\(\Leftrightarrow 3x = 36\)
\(\Leftrightarrow x=12\)
5) 5.(x - 7) + 10.(3 - x) = 20
\(\Leftrightarrow 5x - 35 + 30 - 10x = 20\)
\(\Leftrightarrow -5x = 25\)
\(\Leftrightarrow x = -5\)
6) -4.(x + 1) + 8.(x - 3) = 24
\(\Leftrightarrow -4x - 4 + 8x - 24 = 24\)
\(\Leftrightarrow 4x = 52\)
\(\Leftrightarrow x = 13\)
7) 7.(5 - x) + 5.(x - 2) = 15
\(\Leftrightarrow 35-7x+5x-10=15\)
\(\Leftrightarrow -2x = 15 - 25\)
\(\Leftrightarrow -2x = -10\)
\(\Leftrightarrow x=5\)
8) 4.(x - 1) - 3.(x - 2) = -|-5|
\(\Leftrightarrow 4x - 4 - 3x + 6 = -5\)
\(\Leftrightarrow x = -5-2\)
\(\Leftrightarrow x=-7\)
