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\(31.15.7^2.4-31.49.40=31.49.5.12-31.49.5.8=31.49.5\left(12-1\right)=7595.11=83545\)
Bài này ko có lời giải bạn nhé mk trình bày chi tiết rùi đấy ....
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a, 2 x 31 x 12 + 4 x 6 x 42 + 8 x 27 x 3
= 2 x 12 x 31 + 4 x 6 x 42 + 8 x 3 x 27
= 24 x 31 + 24 x 42 + 24 x 27
= 24 x ( 31 + 24 + 27 )
= 24 x 82
= 1968
b, 2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
= 24 x 53 + 24 x 87 - 24 x 40
= 24 x ( 53 + 87 - 40 )
= 24 x 100
= 2400
c, Tương tự
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a.\(\frac{5}{4}+\frac{3}{7}-\frac{1}{2}=\frac{35+12-14}{28}\)\(=\frac{33}{28}\)
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\(a,3x-31=-40\Rightarrow3x=-9\Rightarrow x=-3\)
\(b,-3x+37=\left(-4\right)^2\Rightarrow-3x=-21\Rightarrow x=7\)
\(c,\left|2x+7\right|=5\)
\(\Rightarrow\left\{{}\begin{matrix}2x+7=5\Rightarrow x=-1\\2x+7=-5\Rightarrow x=-6\end{matrix}\right.\)
\(d,-x+21=15+2x\Rightarrow3x=6\Rightarrow x=2\)
a) Ta có: 3x-31=-40
\(\Leftrightarrow3x=-9\)
hay x=-3
Vậy: x=-3
b) Ta có: \(-3x+37=\left(-4\right)^2\)
\(\Leftrightarrow-3x+37=16\)
\(\Leftrightarrow-3x=16-37=-21\)
hay x=7
Vậy: x=7
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a) - 72 . ( 15 - 49 ) + 15 . ( - 56 + 72 ) = -72 . -34 +15 . 16
= 2448 + 240
= 2688
b) 1532 + ( -168 ) + ( - 1432 ) + ( - 14 ) + 123 = 1364 + ( -1432) + ( -14) +123
= -68 + ( -14 ) +123
= -82 + 123 = 41
c) 75 - 5 . ( 15 - 40 ) - ( - 60 ) = 75 - 5 . (-25 )-(-60)
= 75 - (-125) - ( -60 )
= 200 - ( -60 ) = 260
d) | 31 -17 | - | 15 - 52 | = | 14 | - | -37 |
= 14 - 37
= -23
![](https://rs.olm.vn/images/avt/0.png?1311)
5/17 + -4/9 + -20/31 + -11/31 < x < -3/7 + 7/15 + 4/-7 + 8/15 + 2/3
-175/153<x\(\le\)2/3
-175/153<x\(\le\)102/153
suy ra -175<x\(\le\)153
vậy x bằng (-174/153,-173/153,-172/153,.........,101/153,102/153
31.15.72.4-31.49.40
=31.15.49.4-31.49.40
=31.49(15.4-40)
=31.49.20
=30380