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15.(27+18+6)+15.(23+12)
=15.(27+18+6+23+12)
=15.[(27+23)+(18+12)+6]
=15.(50+30+6)
=15.86
=1290
15 × ( 27 + 18 + 6 ) + 15 × ( 23 + 12)
= 15 × 51 + 15 × 35
= 15 × 51 +35
= 15 × 86
= 1290
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: \(10^2:\left[\left(15-2^3\right)\cdot3+\left(10-12\right):2\right]\)
\(=100:\left[45-24+5-6\right]\)
\(=100:\left(50-30\right)\)
\(=100:20=5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Mình cần gấp . Giải chi tiết nha !
TÍNH NHANH :
12 x ( 22 - 15 ) - 22 x ( 15 - 12 )
12 x 7 - 22 x 3
84 - 66
18
\(=12\times22-12\times15-22\times15-22\times12\)
\(=\left[\left(12\times22\right)-\left(22\times12\right)\right]-\left[\left(12\times15\right)-\left(22\times15\right)\right]\)
\(=0-15\times\left(12-22\right)\)
\(=0-15\times\left(-10\right)\)
\(=0-\left(-150\right)\)
\(=150\)
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![](https://rs.olm.vn/images/avt/0.png?1311)
a)= 21 + (-21)
= 0
b)=15+4.3
=15+12
=27
c) =8.3+36:12-27
=24+3-27
=27-27
=0
![](https://rs.olm.vn/images/avt/0.png?1311)
-15 ( x - 2 ) + 7 ( 3 - x ) = 7
-15x + 30 + 21 - 7x = 7
-15x - 7x = 7 - 21 - 30
-22x = -44
x = ( -44 ) : ( -22)
x = 2
Vậy x = 2
-12 ( x - 5 ) + 7 ( 3 - x ) = 5
-12x + 60 + 21 - 7x = 5
-12x - 7x = 5 - 21 - 60
-19x = -76
x = ( -76 ) : (-19)
x = 4
Vậy x = 4.
# HOK TỐT #
![](https://rs.olm.vn/images/avt/0.png?1311)
12 = 22 . 3
15 = 3 .5
105 = 3 . 5 . 7
BCNN(12,15,105) = 22 . 3 . 5 . 7 = 420
BC(12,15,105) = B(420) = {0;420:840;1260;...}
k nha
12= 22.3
15=3.5
105= 3.5.7
BCNN(12,15,105) = 22 .3.5.7=420
BC (12,15,105)=B(420)={0,420,840,1260,1680,....}
![](https://rs.olm.vn/images/avt/0.png?1311)
-180
-180