Tính một cách hợp lí:
8 . 49 . 20 . 125 . 5
Tính một cách hợp lí:
8 . 49 . 20 . 125 . 5
\(8.49.20.125.5=49.\left(20.5\right).\left(125.8\right)=49.100.1000=4900000\)
8.49.20.125.5
= ( 8.125).(20.5).49
= 1 000 . 100.49
=100000 . 49
=4900000
Tính một cách hợp lí:
\(\dfrac{11}{125}-\dfrac{17}{18}-\dfrac{5}{7}+\dfrac{4}{9}+\dfrac{17}{14}\)
= 11/125 - [(17/18 - 4/9) + (5/7 - 17/14)]
= 11/125 - (1/2 - 1/2)
= 11/125
\(\dfrac{11}{125}-\dfrac{17}{18}-\dfrac{5}{7}+\dfrac{4}{9}+\dfrac{17}{14}=\dfrac{11}{125}-\left(\dfrac{17}{18}-\dfrac{4}{9}\right)+\left(\dfrac{17}{14}-\dfrac{5}{7}\right)=\dfrac{11}{125}-\dfrac{17-4.2}{18}+\dfrac{17-5.2}{14}=\dfrac{11}{125}-\dfrac{9}{18}+\dfrac{7}{14}=\dfrac{11}{125}-\dfrac{1}{2}+\dfrac{1}{2}=\dfrac{11}{125}\)
1. tính bằng cách hợp lí :
a. 5 . 125 . 2 . 41 . 8 = c. 8 . 12 . 125 . 2 =
b. 25 . 7 . 10 . 4 = d. 4 . 36. 25 . 50 =
a) 5 . 125 . 2 . 41 . 8
= (5 . 8) . (125 . 2) . 41
= 40 . 250 . 41
= 10 000 . 41
= 410 000
b) 25 . 7 . 10 . 4
= (25 . 4 ) . (10 . 7)
= 100 . 70
= 7000
Chúc bạn học tốt!! ^^
a,5.125.2.41.8=(125.8).(2.5).41=1000.10.41=410000
b,25.7.10.4=(25.4).70=100.70=7000
c,8.12.125.2=(8.125).12.2=100.24=2400
d,4.36.25.50=(4.25).(2.50).18=100.100.18=180000
c) 8 . 12 . 125
= (125 . 8) . 12
= 1000 . 12
= 12 000
d) 4 . 36 . 25 . 50
= (25 . 4) . (50 . 36)
= 100 . 1800
= 180 000
Chúc bạn học tốt!! ^^
Tính bằng cách hợp lí nhất:
a) (-125) . 4
b) (-2017) . (-2016) . 0
c) (-12) . (-11)
d) (-4) . (-8) . (-25) . (-125)
e) (-2) . (-5) . (-7)
(-2) = âm 2 ; (-5) = âm 5 ; . = nhân
giúp t vs, t càn gấp, tí t đi học r
a) (-125) . 4
= -500
b) (-2017) . (-2016) . 0
= 0
c) (-12) . (-11)
= 132
d) (-4) . (-8) . (-25) . (-125)
= [(-4).(-25)].[(-8).(-125)]
= 100.1000
= 100000
e) (-2).(-5).(-7)
= [(-2).(-5)].(-7)
= 10.(-7)
= -70
a: \(\left(-125\right)\cdot4=-\left(125\cdot4\right)=-500\)
b: \(\left(-2017\right)\cdot\left(-2016\right)\cdot0=0\cdot2016\cdot2017=0\)
c: \(\left(-12\right)\cdot\left(-11\right)=12\cdot11=12\cdot10+12=120+12=132\)
d: \(\left(-4\right)\cdot\left(-8\right)\cdot\left(-25\right)\cdot\left(-125\right)\)
\(=4\cdot8\cdot25\cdot125\)
\(=4\cdot25\cdot8\cdot125\)
\(=100\cdot1000=100000\)
e: \(\left(-2\right)\cdot\left(-5\right)\cdot\left(-7\right)\)
\(=-7\cdot2\cdot5\)
\(=-7\cdot10=-70\)
Thực hiện phép tính một cách hợp lí :
a,123.456+123.789-1245.23
b,2^9:16^2+81^5:3^18-125^7:625^5
123.456+123.789-1245.23
=123.(456+789)-1245.23
=123.1245-1245.23
=1245.(123-23)
=1245.100
=124500
=123.(456+789)-1245.23
=123.1245-1245.23
=1245.(123-23)
=1245.100
=124500
a)(bạn kia làm rồi)
b)2^9:16^2+81^5:3^18-125^7:625^5
=2^9:(2^4)^2+(3^4)^5:3^18-(5^3)^7:(5^4)^5
=2^9:2^8+3^20:3^18-5^21:5^20
=2+3^2+5
=2+9+5
=16
Tính bàng cách hợp lí
1253×75_1755÷5/20142015
thực hiện phép tính một cách hợp lí :
123.456+123.789+1245.23
\(2^9:16^2+81^5:3^{18}-125^7:625^5\)
a)Ta có\(123\times456+123\times789+1245\times23\)
\(=123\left(456+789\right)+1245.23\)
\(=123.1245+1245.23\)
\(=1245\left(123+23\right)\)
\(=1245.146\)
\(=181770\)
b)\(2^9:16^2+81^5:3^{18}-125^7:625^5\)
\(=2^9:\left(2^4\right)^2+\left(3^4\right)^5:3^{18}-\left(5^3\right)^7:\left(5^4\right)^5\)
\(=2^9:2^8+3^{20}:3^{18}-5^{21}:5^{20}\)
\(=2+3^2-5\)
\(=2+9-5\)
\(=6\)
Tính nhanh một cách hợp lí:
(−125). 2. 45. (−8). 50
(−125). 2. 45. (−8). 50
= [ (-125) . (-8) ] . [ 2. 50 ]. 45
= 1000 . 100 . 45
= 100000 . 45
= 4500000
Tính hợp lí:
a) 125. ( -24 ) + 24 . 225
b) 24. ( -125 ) - 125. ( -36 )
c) 512. ( 2- 128 ) - 128. ( -512 )
d) ( -8 ). 25 .( -2 ). 4 .( -5 ). 125
a. 24 x (-125 + 225)
= 24 x 100
=2400
b. -125 x ( 24 -36 )
= -125 x -12
= 1500
c. 512 x (2 -128+128)
= 512 x 2
= 1024
d. \([4.25].\left[\left(-2\right).\left(-5\right)\right].\left[125.\left(-8\right)\right]\)
= 100.10.(-1000)
= -1000000
a. 24 x (-125 + 225)
= 24 x 100
=2400
b. -125 x ( 24 -36 )
= -125 x -12
= 1500
c. 512 x (2 -128+128)
= 512 x 2
= 1024
d.
= 100.10.(-1000)
= -1000000
Tính một cách hợp lí
a) ( - 125 ) . ( + 25 ) . ( - 32 ) . ( - 14 )
b) ( - 2 )3 . ( - 25 ) . ( + 5 ) . ( - 4 )
a) ( - 125 ) . (+ 25 ) . ( - 32 ) . ( - 14)
= [( - 125 ) . ( - 32 )] . [ 25 . ( -14 )]
= 4000 . ( - 350 )
= - 1 400 000
b) ( - 2 )3 . ( - 25 ) . ( +5) . ( - 4 )
= ( -8) . ( -25) . 5 . ( - 4 )
= [( - 8 ) . 5 ] . [( - 25 . ( - 4 )]
= ( - 40 ) . 100
= - 4000
\(\left(-125\right).25.\left(-32\right).\left(-14\right)\)
\(=\left(-125\right).25.\left(-8\right).4.\left(-14\right)\)
\(=\left[\left(-125\right).\left(-8\right)\right].\left(25.4\right).\left(-14\right)\)
\(=1000.100.\left(-14\right)\)
\(=-1400000\)
\(\left(-2\right)^3.\left(-25\right).5.\left(-4\right)\)
\(=\left(-8\right).\left(-25\right).5.\left(-4\right)\)
\(=\left[\left(-25\right).\left(-4\right)\right].\left[\left(-8\right).5\right]\)
\(=100.\left(-40\right)=-4000\)