Giúp em câu này:
-94 x 12 + (-2) x 6 x (-5) + 12 x (-1)
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1. a
\(\dfrac{8}{5}-\dfrac{5}{6}\cdot\dfrac{3}{4}\)
\(=\dfrac{8}{5}-\dfrac{5\cdot3}{3\cdot2\cdot4}\)
\(=\dfrac{8}{5}-\dfrac{5}{8}=\dfrac{39}{40}\)
1.b
\(=\dfrac{7}{8}+\dfrac{5}{6}\cdot\dfrac{3}{2}\)
\(=\dfrac{7}{8}+\dfrac{5\cdot3}{3\cdot2\cdot2}\)
\(=\dfrac{7}{8}+\dfrac{5}{4}=\dfrac{17}{8}\)
2.a
\(\dfrac{4}{5}+x=\dfrac{11}{10}\)
\(x=\dfrac{11}{10}-\dfrac{4}{5}=\dfrac{3}{10}\)
2.b
\(x-\dfrac{3}{4}=\dfrac{5}{7}\)
\(x=\dfrac{5}{7}+\dfrac{3}{4}=\dfrac{41}{28}\)
1) = \(\frac{3}{5}\)
2) =\(\frac{6}{7}\)
3)\(\frac{9}{13}\)
4)\(\frac{4}{13}\)
Câu 1)
1/5*x=4/6
x=4/6/1/5
x=10/3
Câu 3)x/6*5/8=5/12
x/6=5/12/5/8
x/6=2/3
x/6=4/6
Vây x=4
Câu 3)
5/9/3/x=5/27
3/x=5/9/5/27
3/x=3
Vây x=1
a,sửa đề : đk x khác -2; 2
\(x^2+x-2+5x-10=12+x^2-4\)
\(\Leftrightarrow6x-20=0\Leftrightarrow x=\dfrac{10}{3}\left(tm\right)\)
b, \(3x-12+5+5x=105\Leftrightarrow8x=112\Leftrightarrow x=14\)
c, \(3x^2+14x-49=-\left(x^2+2x-15\right)\)
\(\Leftrightarrow4x^2+16x-34=0\Leftrightarrow x=\dfrac{-4\pm5\sqrt{2}}{2}\)
a. ko hỉu đề lắm :v
b.\(\dfrac{x-4}{5}+\dfrac{1+x}{3}=7\)
\(\Leftrightarrow\dfrac{3\left(x-4\right)+5\left(1+x\right)}{15}=\dfrac{105}{15}\)
\(\Leftrightarrow3\left(x-4\right)+5\left(1+x\right)=105\)
\(\Leftrightarrow3x-12+5+5x-105=0\)
\(\Leftrightarrow8x-112=0\)
\(\Leftrightarrow8x=112\)
\(\Leftrightarrow x=14\)
c.\(\left(3x-7\right)\left(x+7\right)=\left(5+x\right)\left(3-x\right)\)
\(\Leftrightarrow3x^2+21x-7x-49=15-5x+3x-x^2\)
\(\Leftrightarrow4x^2+16x-64=0\)
Nghiệm xấu lắm bạn
231 - ( x - 6 ) = 1339 : 13
231 - ( x - 6 ) = 103
x = 231 - 103 + 6
x = 128 + 6
x = 134
=> 72 - 20x - 36x - 84 = 30x - 240 - 6x + 84
=> (72 - 84 ) - (20x + 36x ) = (30x - 6x ) - 240 + 84
=> -12 - 56x = 24x - 156
=> -12 + 156 = 24x + 56x
=> 144 = 80x
=> x = 144 : 80
=> x = 9/5
-94 x 12 + (-2) x 6 x (-5) + 12 x (-1)
= -94 x 12 + 12 x 5 + 12 x (-1)
= 12 x (-94 + 5 - 1)
= 12 x (-90)
= 1080.