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Bài 3:
a: Ta có: 60-3(x-2)=51
\(\Leftrightarrow x-2=3\)
hay x=5
b: Ta có: \(4x-20=25:2^2\)
\(\Leftrightarrow4x=\dfrac{25}{4}+20=\dfrac{105}{4}\)
hay \(x=\dfrac{105}{16}\)
c: Ta có: \(8\cdot6+288:\left(x-3\right)^2=50\)
\(\Leftrightarrow288:\left(x-3\right)^2=50-48=2\)
\(\Leftrightarrow\left(x-3\right)^2=144\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=12\\x-3=-12\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=15\\x=-9\end{matrix}\right.\)
a) 38 . (72 + 48) . 62 . (74 + 46)
=38 . 120 . 62 . 120
= 120 . (62 + 38)
= 120 . 100
= 12 000
b) 92 . (278 - 68) : (70 . 92)
=92 . 210 : 70 . 92
= \(\frac{92.210}{70.92}\)
=\(\frac{210}{70}\)= 3
kích mình nhé
36.(-54)+92.(-18)
=36.(-54)+(2.46).(-18)
=36.(-54)+(-46).36
=36.[(-54)+(-46)]
=36.(-100)
=-3600
Ta có 46 x 128 + 92 x 36 =46 x 128 +(2x46) x 36
=46 x 128 +46x72
=46x(128+72)= 46x200=9200
\(\text{46 x 128 + 92 x 36}\)
= \(\text{46 . 128 +( 2 . 46 ) . 36}\)
= \(\text{46 . 128 +46. ( 36 . 2 ) }\)
\(\text{= 46 . 128 + 46 . 72 }\)
= \(46\left(72+128\right)\)
= \(46.200\)
= \(9200\)
108 . 12 + 25 . 92 + 13 . 108
= 108 . ( 12 + 13 ) + 25 . 92
= 108 . 25 + 25 . 92
= 25 . ( 108 + 92 )
= 25 . 200
= 5000
\(108.12+25.92+13.108\)
\(=108.\left(12+13\right)+25.92\)
\(=108.25+25.92\)
\(=25.\left(108+92\right)\)
\(=25.200\)
\(=5000\)
\(\frac{36}{47}-\frac{92}{29}-\frac{36}{47}+\frac{90}{29}\)
\(=\left(\frac{36}{47}-\frac{36}{47}\right)+\left(\frac{-92}{29}+\frac{90}{29}\right)\)
\(=0+\frac{-2}{29}\)
\(=\frac{-2}{29}\)
\(\frac{92}{3}+\frac{66}{35}+\frac{38}{63}+\frac{86}{15}=\left(\frac{92}{3}+\frac{86}{15}\right)+\left(\frac{66}{35}+\frac{38}{63}\right)\)
\(=\frac{182}{5}+\frac{112}{45}=\frac{1638}{45}+\frac{112}{45}=\frac{350}{9}\)