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Ta có
4(18 – 5x) – 12(3x – 7) = 15(2x – 16) – 6(x + 14)
ó 72 – 20x – 36x + 84 = 30x – 240 – 6x – 84
ó -56x + 156 = 24x – 324
ó 24x + 56x = 156 +324 ó 80x = 480 ó x = 6
Vậy x = 6
Đáp án cần chọn là: C
\(\text{a) 7-2x=22-9x}\)
\(\Leftrightarrow\text{7-2x-22+9x=0}\)
\(\Leftrightarrow-15+7x=0\)
\(\Leftrightarrow7x=15\)
\(\Leftrightarrow x=\frac{15}{7}\)
Học tốt
#Thảo Vy#
a) \(3x-2=2x-3\)
\(\Leftrightarrow x+1=0\)
\(\Leftrightarrow x=-1\)
b) \(3-4y+24+6y=y+27+3y\)
\(\Leftrightarrow-2y=0\Leftrightarrow y=0\)
c) \(7-2x=22-3x\)
\(\Leftrightarrow x-15=0\)
\(\Leftrightarrow x=15\)
d) \(8x-3=5x+12\)
\(\Leftrightarrow3x-15=0\Leftrightarrow x=5\)
a) \(x^2+7x+12\)
\(=x^2+3x+4x+12\)
\(=x\left(x+3\right)+4\left(x+3\right)\)
\(=\left(x+3\right)\left(x+4\right)\)
b) \(3x^2-5x+2\)
\(=3x^2-3x-2x+2\)
\(=3x\left(x-1\right)-2\left(x-1\right)\)
\(=\left(x-1\right)\left(3x-2\right)\)
a: \(\dfrac{x^2-5x+6}{x^2+7x+12}:\dfrac{x^2-4x+4}{x^2+3x}\)
\(=\dfrac{\left(x-2\right)\left(x-3\right)}{\left(x+3\right)\left(x+4\right)}\cdot\dfrac{x\left(x+3\right)}{\left(x-2\right)^2}\)
\(=\dfrac{x\left(x-3\right)}{\left(x-2\right)\left(x+4\right)}\)
b: \(\dfrac{x^2+2x-3}{x^2+3x-10}:\dfrac{x^2+7x+12}{x^2-9x+14}\)
\(=\dfrac{\left(x+3\right)\left(x-1\right)}{\left(x+5\right)\left(x-2\right)}\cdot\dfrac{\left(x-2\right)\left(x-7\right)}{\left(x+3\right)\left(x+4\right)}\)
\(=\dfrac{\left(x-1\right)\left(x-7\right)}{\left(x+5\right)\left(x+4\right)}\)

ngu moi di hoi
\(2x+5x=12-9x\)
\(\Rightarrow7x=12-9x\)
\(\Rightarrow7x+9x=12\)
\(\Rightarrow16x=12\)
\(\Rightarrow x=\frac{3}{4}\)
\(2x+5x=12-9x\)
\(\Leftrightarrow2x+5x+9x=12\)
\(\Leftrightarrow16x=12\)
\(\Leftrightarrow x=\frac{12}{16}\)
2x + 5x = 12 - 9x
<=> 7x + 9x = 12
<=> 16x = 12
<=> x = 12/16 = 3/4
Vậy phương trình có nghiệm x = 3/4
Trả lời:
2x + 5x = 12 - 9x
<=> 7x = 12 - 9x
<=> 7x + 9x = 12
<=> 16x = 12
<=> x = 3/4
Vậy S = { 3/4 }