Question

Dạng 3: vận dụng các quy tắc: qt chuyển vế,qtdấu ngoặc, nhân phá ngoặc

a)3x –10 = 2x + 13

b) x + 12 = -5 –x

c) x + 5 = 10 –x

d)6x + 23= 2x –12

e) 12 –x = x + 1

f) 14 + 4x = 3x + 20

g) 2.(x-1) + 3(x-2) = x -4

h) 3.(4 –x) –2.( x-1) = x + 20

i) 4.( 2x + 7) –3.(3x –2) = 24

k) 3(x –2) + 2x = 10

Answer 1

a) \(3x-10=2x+13\Leftrightarrow x=13+10=23\)

b) \(x+12=-5-x\Leftrightarrow2x=-17\Leftrightarrow x=-\frac{17}{2}\)

c) \(x+5=10-x\Leftrightarrow2x=5\Leftrightarrow x=\frac{5}{2}\)

d) \(6x+23=2x-12\Leftrightarrow4x=-35\Leftrightarrow x=-\frac{35}{4}\)

e) \(12-x=x+1\Leftrightarrow2x=11\Leftrightarrow x=\frac{11}{2}\)

f) \(14+4x=3x+20\Leftrightarrow x=20-14=6\)

Answer 2

g) \(2\left(x-1\right)+3\left(x-2\right)=x-4\Leftrightarrow2x-2+3x-6=x-4\)

\(\Leftrightarrow5x-8=x-4\Leftrightarrow4x=4\Leftrightarrow x=1\)

h ) \(3\left(4-x\right)-2\left(x-1\right)=x+20\Leftrightarrow12-3x-2x+2=x+20\)

\(\Leftrightarrow14-5x=x+20\Leftrightarrow6x=-6\Leftrightarrow x=-1\)

i ) \(4\left(2x+7\right)-3\left(3x-2\right)=24\Leftrightarrow8x+28-9x+6=24\)

\(\Leftrightarrow34-x=24\Leftrightarrow x=34-24=10\)

k) \(3\left(x-2\right)+2x=10\Leftrightarrow3x-6+2x=5x-6=10\)

\(\Leftrightarrow5x=10+6=16\Leftrightarrow x=\frac{16}{5}\)

Tự KL cho các phần