\(\left(-37\right)+54+\left(-70\right)+\left(-163\right)+246\)
Tính nhanh :
a) \(\left(-4\right)\left(+125\right)\left(-25\right)\left(-6\right)\left(-8\right)\)
b) \(\left(-98\right)\left(1-246\right)-246.98\)
Sách Giáo Khoa
a) (-4).(+125).(-25).(-6).(-8) = [(-4).(-25)].[(+125).(-8)].(-6) = 100.(-1000).(-6) = 600000 b) (-98).(1 - 246) – 246.98 = -98 + 98.246 - 246.98 = -98 + 98.(246 - 246) = -98 + 98.0 = -98a) (-4).(+125).(-25).(-6).(-8)
= [(-4).(-25)].[(+125).(-8)].(-6)
= 100.(-1000).(-6)
= 600000
b) (-98).(1 - 246) – 246.98
= -98 + 98.246 - 246.98
= -98 + 98.(246 - 246)
= -98 + 98.0
= -98
a)(-4).(+125).(-25).(-6).(-8)
=4 . 125 . 25. 6 . 8
=(4.25).(125.8).6
=100 . 1000.6
= 600000
b)(-98).(1-246)-246.98
= (-98)-(-245)-246.98
= 98. 245 -246.98
= 98.(245-246)
= 98.(-1)
= -98
-37+54+(-70)+ (-163)+246=?
\(-37+54+\left(-70\right)+\left(-163\right)+246\\ =-37+54-70-163+246\\ =\left(-37-163\right)+\left(54+246\right)-70\\ =-200+300-70\\ =100-70\\ =30.\)
(-37)+54+(-70)+(-163)+246
(-37)+54+(-70)+(-163)+246
=[(-37)+(-163)]+(54+246)+(-70)
=[-(37+163)]+300+(-70)
=-200+300+(-70)
=[+(300-200)]+(-70)
=100+(-70)
=+(100-70)
=30
tính nhanh
a) A=\(2018^2-2017\cdot2019\)
b) B=\(9^8\cdot2^8-\left(18^4-1\right)\cdot\left(18^4+1\right)\)
c) C=\(163^2+74\cdot163+37^2\)
d) D=\(\dfrac{2018^3-1}{2018^2+2019}\)
e) E=\(\left(2+1\right)\cdot\left(2^2+1\right)\cdot\left(2^4+1\right)\cdot\left(2^8+1\right)\cdot\left(2^{16}+1\right)-2^{32}\)
Lời giải:
\(A=2018^2-2017.2019=2018^2-(2018-1)(2018+1)\)
\(=2018^2-(2018^2-1^2)=1\)
\(B=9^8.2^8-(18^4-1)(18^4+1)\)
\(=(9.2)^8-[(18^4)^2-1^2]\)
\(=18^8-(18^8-1)=1\)
\(C=163^2+74.163+37^2=163^2+2.37.163+37^2\)
\(=(163+37)^2=200^2=40000\)
\(D=\frac{2018^3-1}{2018^2+2019}=\frac{(2018-1)(2018^2+2018+1)}{2018^2+2019}\)
\(=\frac{2017(2018^2+2019)}{2018^2+2019}=2017\)
Sử dụng công thức \((a-b)(a+b)=a^2-b^2\)
\(E=(2+1)(2^2+1)(2^4+1)(2^8+1)(2^{16}+1)-2^{32}\)
\(=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)(2^{16}+1)-2^{32}\)
\(=(2^2-1)(2^2+1)(2^4+1)(2^8+1)(2^{16}+1)-2^{32}\)
\(=(2^4-1)(2^4+1)(2^8+1)(2^{16}+1)-2^{32}\)
\(=(2^8-1)(2^8+1)(2^{16}+1)-2^{32}\)
\(=(2^{16}-1)(2^{16}+1)-2^{32}\)
\(=(2^{32}-1)-2^{32}=-1\)
Tính :
a) \(29.\left(-13\right)+27.\left(-27\right)+\left(-14\right).\left(-29\right)\)
b) \(17.\left(-37\right)-23.37-46.\left(-37\right)\)
Sao chỉ có mỗi tính thôi mà bạn cũng không làm được?
Tính:
\(-3^2+\left\{-54:\left[-2^8+7\right]\cdot\left(-2\right)^2\right\}\)
Tính hợp lí :
\(31\cdot\left(-18\right)+31\cdot\left(-81\right)-31\)
\(\left(-12\right)\cdot47+\left(-12\right)\cdot52+\left(-12\right)\)
\(13\cdot\left(23+22\right)-3\cdot\left(17+28\right)\)
\(-48+48\cdot\left(-78\right)+48\cdot\left(-21\right)\)
`#3107.101107`
`-3^2 + {-54 \div [-2^8 + 7] * (-2)^2}`
`= -9 + [-54 \div (-256 + 7) * 4]`
`= -9 + [-54 \div (-249) * 4]`
`= -9 + (18/83 * 4)`
`= -9 + 72/83`
`= -675/83`
______
`31 * (-18) + 31 * (-81) - 31`
`= 31 * (-18 - 81 - 1)`
`= 31 * (-100)`
`= -3100`
___
`(-12) * 47 + (-12) * 52 + (-12)`
`= (-12) * (47 + 52 + 1)`
`= (-12) * 100`
`= -1200`
___
`13 * (23 + 22) - 3 * (17 + 28)`
`= 13 * 45 - 3 * 45`
`= 45 * (13 - 3)`
`= 45 * 10`
`= 450`
____
`-48 + 48 * (-78) + 48 * (-21)`
`= 48 * (-1 - 78 - 21)`
`= 48 * (-100)`
`= -4800`
Tính một cách hợp lí:
a) \(\left(-16\right).\left(-7\right).5;\) b) \(11.\left(-12\right)+11.\left(-18\right);\)
c) \(87.\left(-19\right)-37.\left(-19\right);\) d) \(41.81.\left(-451\right).0.\)
a) (- 16) . (- 7) . 5 = [(- 16) . 5] . (- 7) = 560.
b) 11 . (- 12) + 11 . (- 18) = 11 . [(- 12) + (- 18)] = 11 . [- (12 + 18)] = 11 . (- 30) = - 330.
c) 87 . (- 19) – 37 . (- 19) = (- 19) . (87 – 37) = (- 19) . 50 = - 950.
d) 41 . 81 . (- 451) . 0 = 0.
a) (- 16) . (- 7) . 5 = [(- 16) . 5] . (- 7) = 560.
b) 11 . (- 12) + 11 . (- 18) = 11 . [(- 12) + (- 18)] = 11 . [- (12 + 18)] = 11 . (- 30) = - 330.
c) 87 . (- 19) – 37 . (- 19) = (- 19) . (87 – 37) = (- 19) . 50 = - 950.
d) 41 . 81 . (- 451) . 0 = 0.
a) (-16).(-7).5
=16.7.5 = 2.8.7.5
=(2.5).(8.7) = 56 . 10 =560
b) 11 . (-12) + 11.(-18)
=11 . (-12 -18)
=11.(-20) = -220
c) 87.(-19) - 37 .(-19)
=(-87).19 + 37.19
=19 . (-87+37)
=19.(-50)
= -950
d) 41.81.(-451).0
= (mọi số nhân 0 đều bằng 0)
Thực hiện các phép tính sau:
a) 23+45
b) \(\left( { - 42} \right) + \left( { - 54} \right)\)
c) \(2025 + \left( { - 2025} \right)\);
d) \(15 + \left( { - 14} \right)\);
e) \(35 + \left( { - 135} \right)\)
a) 23 + 45 = 68
b) \(\left( { - 42} \right) + \left( { - 54} \right) = - \left( {42 + 54} \right) = - 96\)
c) \(2025 + \left( { - 2025} \right) = 0\) vì 2025 và \( - 2025\) là 2 số đối nhau.
d) \(15 + \left( { - 14} \right) = 15 - 14 = 1\);
e) \(35 + \left( { - 135} \right) = - \left( {135 - 35} \right) = - 100\)
Tính nhanh - 37 + 54 + -70 + -163 + 246
-37 + 54 + (-70) + (-163 ) + 246
= [ (-37) + (-163) ] + ( 54 + 246 ) + (-70)
= -200 + 300 + (-70)
= 100 + (-70)
= 30
dap an cua Den do