(-28):(-175)=16:(-5x)
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b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
a) Ta có: \(4\sqrt{28}+3\sqrt{63}-3\sqrt{112}-2\sqrt{175}\)
\(=8\sqrt{7}+9\sqrt{7}-12\sqrt{7}-10\sqrt{7}\)
\(=-5\sqrt{7}\)
b) Ta có: \(\sqrt{5}\left(\sqrt{5}-3\sqrt{20}+2\sqrt{80}\right)\)
\(=\sqrt{5}\left(\sqrt{5}-6\sqrt{5}+8\sqrt{5}\right)\)
\(=\sqrt{5}\cdot3\sqrt{5}=15\)
c) Ta có: \(\left(\sqrt{\dfrac{16}{3}}-\sqrt{\dfrac{25}{3}}\right)\cdot\sqrt{3}\)
\(=\dfrac{-1}{\sqrt{3}}\cdot\sqrt{3}\)
=-1
e) Ta có: \(\left(\sqrt{\dfrac{32}{3}}-\sqrt{54}+\sqrt{\dfrac{50}{3}}\right)\cdot\sqrt{6}\)
\(=\left(\dfrac{4\sqrt{2}}{\sqrt{3}}+\dfrac{5\sqrt{2}}{\sqrt{3}}-3\sqrt{6}\right)\cdot\sqrt{6}\)
\(=\dfrac{9\sqrt{12}}{\sqrt{3}}-18\)
\(=0\)
f) Ta có: \(\left(\sqrt{6}-2\right)\left(\sqrt{3}+\sqrt{2}\right)\)
\(=3\sqrt{2}+2\sqrt{3}-2\sqrt{2}-2\sqrt{2}\)
\(=\sqrt{2}\)
a, 117 - \(x\) = 28 - (-7)
117 - \(x\) = 28 + 7
117 - \(x\) = 35
\(x\) = 117 - 35
\(x\) = 82
b, \(x\) - (-38 - 2\(x\)) = (-3) - 8 + 2\(x\)
\(x\) + 38 + 2\(x\) = - 11 + 2\(x\)
3\(x\) + 38 = - 11 + 2\(x\)
3\(x\) - 2\(x\) = - 11 - 38
\(x\) = - 49
Bài làm
Bài 1 : Tính nhanh
a) 10000 - 47x 7 -47 x 28
= 47x(10000-28)
=47x9972
=468684
b) 54x 47 - 53x 47 - 47
=47x(54-53)-47
=47x1-47
=47-47
=0
c)175 x 1274 - 175 x 273 - 175
=175x(1274-273)-175
=175x1001-175
=175175-175
=175000
# Chúc bạn học tốt #
a) ( -48 ) + 48 . ( -78 ) + 48 . ( -24 )
= 48 . ( -1 - 78 - 24 )
= 48 . ( -103 )
= -4944
b) 31 . ( -18 ) + 31 . ( -81 ) - 31
= 31 . ( -18 - 81 - 1 )
= 31 . 62
= -3100
c) 35 x 18 - 5 x 7 x 28
= 35 x 18 - 35 x 28
= 35 x ( 18 - 28 )
= 35 x ( -10 )
= -350
d) ( -16 ) + 24 + 16 - 34
= [ ( -16 ) + 16 ] + ( 24 - 34 )
= 0 + ( - 10 )
= -10
Lời giải:
$\frac{7}{18}+\frac{1}{25}: (\frac{72}{175}: 28)$
$=\frac{7}{18}+\frac{1}{25}: \frac{18}{1225}$
$=\frac{7}{18}+\frac{49}{18}=\frac{7+49}{18}=\frac{56}{18}=\frac{28}{9}$
\(175-5\times\left(x-10\right)=25\)
\(\Rightarrow5\times\left(x-10\right)=175-25\)
\(\Rightarrow5\times\left(x-10\right)=150\)
\(\Rightarrow x-10=150:5\)
\(\Rightarrow x-10=30\)
\(\Rightarrow x=30+10\)
\(\Rightarrow x=40\)
Học tốt #
\(175-5\left(x-10\right)=25\)
\(\Leftrightarrow5\left(x-10\right)=150\)
\(\Leftrightarrow x-10=30\)
\(\Leftrightarrow x=40\)
hok tốt nhé!
x= 125 nha
Ta có: (-28):(-175)=16:(-5x)
=> 0.16 = 16 : (-5x)
=> -5x = 16 : 0,16
=> -5x = 100
=> x = 100: (-5)
=> x = -20
Vậy ....