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nhân chéo chia ngang
x= -7*36/12=-21
muốn chắc chắn thì thử lại
\(\frac{-7}{12}=\frac{21}{36}\)theo quy đồng cũng đúng
Viết lại là:
\(\frac{-7}{12}=\frac{x}{36}\)
=> \(-7.36=12.x\)
=> \(-252=12.x\)
=> \(x=\frac{-252}{12}\)
=> \(x=-21\)
a) 3(x + 5) - 8 = x + 17
=> 3x + 15 - 8 = x + 17
=> 3x + 7 = x + 17
=> 3x - x = 17 - 7
=> 2x = 10
=> x = 10 : 2
=> x = 5
b) 5(x + 3) - 10 = 2x - 19
=> 5x + 15 - 10 = 2x - 19
=> 5x + 5 = 2x - 19
=> 5x - 2x = -19 - 5
=> 3x = -24
=> x = -24 : 3
=> x = -8
a. 3x+15-8=x+17
3x-x=17-15+8
2x=10
x=5
b.5x+15-10=2x-19
5x+5=2x-19
5x-2x=-19-5
3x=-24
x=-8
thank
a) \(5x+x=39-3^{11}:3^9\)
\(\Leftrightarrow6x=39-3^2\)
\(\Leftrightarrow6x=30\)
\(\Leftrightarrow x=5\)
b) \(2^x:2^5=16\)
\(\Leftrightarrow2^x:2^5=2^4\)
\(\Leftrightarrow2^x=2^4.2^5\)
\(\Leftrightarrow2^x=2^9\)
\(\Leftrightarrow x=9\)
c) \(7x-x=5^{21}:5^{19}+3.2^2-7^0\)
\(\Leftrightarrow6x=5^2+3.4-1\)
\(\Leftrightarrow6x=36\)
\(\Leftrightarrow x=6\)
d) \(7x-2x=6^{17}:6^{15}+44:11\)
\(\Leftrightarrow5x=6^2+4\)
\(\Leftrightarrow5x=40\)
\(\Leftrightarrow x=8\)
a)⇔6x=39-32
⇔6x=30
⇔ x=5
b)2x:25=16
⇔2x=24.25
⇔ 2x=29
⇔ x=9
c)⇔6x=52+3.22-1
⇔ 6x= 36
⇔ x=6
d)⇔5x=62+4
⇔ 5x=40
⇔ x=8
a/ \(\left|5x+\frac{3}{4}\right|-\frac{5}{4}=2\)
\(\left|5x+\frac{3}{4}\right|=\frac{13}{4}\)
- / \(5x+\frac{3}{4}=\frac{13}{4}\)
\(5x=\frac{5}{2}\)
\(x=\frac{1}{2}\) - / \(5x+\frac{3}{4}=-\frac{13}{4}\)
\(5x=-4\)
\(x=-\frac{4}{5}\)
\(\Rightarrow x=\left\{\frac{1}{2};-\frac{4}{5}\right\}\)
b/\(\frac{3}{2}-\left|\frac{1}{2}x+1\right|=\frac{1}{4}\)
\(\left|\frac{1}{2}x+1\right|=\frac{5}{4}\)
1/\(\frac{1}{2}x+1=\frac{5}{4}\)
\(\frac{1}{2}x=\frac{1}{4}\)
\(x=\frac{1}{2}\)
2/\(\frac{1}{2}x+1=-\frac{5}{4}\)
\(\frac{1}{2}x=-\frac{9}{4}\)
\(x=-\frac{9}{2}\)
\(\Rightarrow x=\left\{\frac{1}{2};-\frac{9}{2}\right\}\)
13 - l x + 5 l = 13
\(\Rightarrow\)l x + 5 l = 13 -13
\(\Rightarrow\)l x + 5 l = 0
\(\Rightarrow\)x + 5 = 0
\(\Rightarrow\)x = 0 - 5
\(\Rightarrow\)x = -5
Ta có: 13 - | x + 5 | = 13
\(\Rightarrow\left|x+5\right|=13-13\)
\(\Rightarrow\left|x+5\right|=0\Rightarrow x+5=0\)
\(\Rightarrow x=-5\)
Chúc bạn học tốt
a: \(\Leftrightarrow6x=30\)
hay x=5
b: \(\Leftrightarrow6x=25+12-1=36\)
hay x=6