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1a) -54 . 76 + 12 .(-76) + 76.(-34)
= (-54 - 12 - 34).76
= -100 . 76
= -176
b) 37.(63 - 24) - 63.(24 + 37)
= 37 . 63 - 37 . 24 - 63.24 - 63 . 37
= (37.63 - 63.37) - (37 + 63) . 24
= 0 - 100 . 24
= - 2400
2a) x + (-27) = -23 - x
=> x + x = -23 + 27
=> 2x = 4
=> x = 4 : 2
=> x = 2
b) xy + 2x - y = 15
=> x(y + 2) - y = 15
=> x(y + 2) - (y + 2) = 13
=> (x - 1)(y + 2) = 13 = 1 . 13 = 13 . 1
Lập bảng :
x - 1 | 1 | -1 | 13 | -13 |
y + 2 | 13 | -13 | 1 | -1 |
x | 2 | 0 | 14 | -12 |
y | 11 | -15 | -1 | -3 |
Vậy ...
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Ta có : 19 x 64 + 76 x 34
= 19 x 64 + 19 x 4 x 34
= 19 x 64 + 19 x 136
= 19 x (64 + 136)
= 19 x 200
= 3800
19 x 64 + 76 x 34
= 38 x 32 + 38 x 68
= 38 x ( 32+68)
= 38 x 100
3800
![](https://rs.olm.vn/images/avt/0.png?1311)
\(19\cdot64+76\cdot34\)
\(=19\cdot64+19\cdot4\cdot34\)
\(=19\cdot64+19\cdot136\)
\(=19\cdot\left(64+136\right)\)
\(=19\cdot200\)
\(=3800\)
19 x 64 + 76 x 34
= 38 x 32 + 38 x 68
= 38 x ( 32 + 68)
= 38 x 100
= 3800
![](https://rs.olm.vn/images/avt/0.png?1311)
b) 35 x 24 + 35 x 76 +55 x 19 +55 x 91
= 35 x ( 24 + 76 ) + 55 x ( 19 + 91 )
= 35 x100 +55 x 100
= 100 x ( 55 + 35 )
= 90 x 100 =9 000
c) \(6\cdot25\cdot4+4\cdot19\cdot6-2\cdot14\cdot12\)
\(=24\cdot25+24\cdot19-24\cdot14\)
\(=24\left(25+19-14\right)\)
\(=24\cdot30=720\)
d) \(19\cdot64+76\cdot34\)
\(=76\cdot19+76\cdot34\)
\(=76\left(19+34\right)=76\cdot53=4028\)
a) 2 x 16 x 50 x 25
= ( 2 x 50 ) x ( 16 x 25 )
= 100 x 400
= 40 000
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 19 x 64 + 76 x 34 = 19 x 64 + 19 x 4 x 34 = 19 x (64 + 4 x 34) = 19 x 200 = 3800
b) 35 x 12 + 65 x 13 = 35 x 12 + 65 x 12 + 65 = 12 x (35 + 65) + 65 = 12 x 100 + 65 = 1265
c) 136 x 68 + 16 x 272 = 136 x 68 + 16 x 2 x 136 = 136 x (68 + 16 x 2) = 136 x 100 = 13600
![](https://rs.olm.vn/images/avt/0.png?1311)
5, 31+1240++1829=3100
6. -19+836+1829=2646
7. 54.43-32.35=2322-1120=1202
8 2018(31+16+50)=2018.97=195746
9. 16(34-21+55)=16.68=1088
10. 63(29-31-98)=63.(-100)=-6300
![](https://rs.olm.vn/images/avt/0.png?1311)
a)24.53+24.87+24.40
=24.(53+87+40)=24.180=(24.18).10
=432.10=4320
b)(19.4).16+76.34
=76.16+76.34
=76.(16+34)
=38.(2.50)
=38.100=3800
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (-54).76 + 12.(-76) - 76.(-34)
= (-54).76 + (-12).76 - 76.(-34)
= 76. [(-54) + (-12) - (-34)]
= 76. (-32)
= -2432
19 x 63 + 76 x 34 = 19 x 63 + 19 x 4 x 34 = 19 x 63 + 19 x 136 = 19 x (63 + 136) = 19 x 199 = 3781
chắc bằng 3781