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a ) x = 5 6 ; b ) x = 8 7 ; c ) x = − 11 14 − ; d ) x = − 13 12
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TK
a) (35 - 15).(-4) + 24.(-13 - 17)
= 20.(-4) + 24.(-30)
= (-80) + (-720)
b) (-13).(57 - 34) +57. (13 - 45)
= (-13).23 + 57.(-32)
= (-299) + (-1824)
= -2123
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a) | -18 | + ( -12 )
= 18 - 12
= 6
b) ( -20 ) + | -88 |
= -20 + 88
= 68
c) | -37 | + ( - | 15 | )
= 37 - 15
= 22
d) 99 - [ 109 + ( -9 ) ]
= 99 - 100
= -1
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\(\left(-22\right)\cdot\left(-5\right)>0\)
\(\left(-7\right)\cdot20< -7\)
(-22).(-5)và 0
do 2 số nguyên âm nhân với nhau ra số nguyên dương nên ta có thể rút gọn biểu thức thành 22.5 và 0 từ đó => 22.5>0
(-7).20 < -7
(-39).12 = 39.(-12)
(35-15).(-4)+24(-13-17)=30.(-4)+24(-13-17)=-120+24.30=-120+720=600
(-13)(57-34)+57(13-45)=-13.57-(-13).34+57.13-57.45=13.(-57)-13.(-34)+57.13-57.45=13(-57-(-34)+57)-57.45=13.34-57.45=442-2565=-2123
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a) \(\left(-17\right)\cdot32+17\cdot\left(-68\right)-17\)
\(=17\cdot\left(-32-68-1\right)\)
\(=17\cdot\left(-101\right)\)
\(=17\cdot\left(-100-1\right)\)
\(=-1700-17\)
\(=-1717\)
b) \(25\cdot\left(34-89\right)+25\cdot89\)
\(=25\cdot\left(34-89+89\right)\)
\(=25\cdot34\)
\(=850\)
c) \(-145\cdot\left(13-57\right)+57\cdot\left(10-145\right)\)
\(=-145\cdot13+145\cdot57+57\cdot10-145\cdot57\)
\(=-145\cdot\left(13+57\right)+57\cdot\left(145+10\right)\)
\(=-145\cdot70+57\cdot155\)
\(=-10150+8835\)
\(=-1315\)
`@` `\text {Ans}`
`\downarrow`
`a)`
\((- 17) . 32 + 17 . (- 68) – 17 \)
`= (-17). (32 + 68 + 1) `
`= (-17). 101`
`= -1717`
`b)`
\(25 . (34 – 89) + 25 . 89\)
`= 25. (34 - 89 + 89)`
`= 25. 34`
`= 850`
`c)`
\(– 145. (13 – 57) + 57. (10 – 145)\)
`= (-145). 13 - (-145). 57 + 57.10 + 57. (-145)`
`= (-145). (13 - 57 + 57) + 57.10`
`= (-145). 13 + 570`
`= -1885 + 570 = -1315`
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\(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)
\(=\left(\frac{157}{8}:\frac{7}{12}-\frac{53}{4}:\frac{7}{12}\right).\frac{4}{5}\)
\(=\left[\left(\frac{157}{8}-\frac{53}{4}\right):\frac{7}{12}\right].\frac{4}{5}\)
\(=\left[\frac{51}{8}:\frac{7}{12}\right].\frac{4}{5}\)
\(=\frac{153}{14}.\frac{4}{5}\)
\(=\frac{306}{35}\)
\(\left(\frac{-2}{5}+\frac{3}{7}\right)-\left(\frac{4}{9}+\frac{12}{20}-\frac{13}{35}\right)+\frac{7}{35}\)
\(=\frac{1}{35}-\frac{212}{315}+\frac{7}{35}\)
\(=\frac{1}{35}+\frac{-212}{315}+\frac{7}{35}\)
\(=\frac{9}{315}+\frac{-212}{315}+\frac{63}{315}\)
\(=\frac{-140}{315}=\frac{-4}{9}\)
D