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Giải:
a,\(\dfrac{2^5.3^2}{2^3.3}=2^2.3=12\)
b, \(\dfrac{5^3.6}{5.2^2}=\dfrac{5^3.2.3}{5.2^2}=\dfrac{5^2.3}{2}=37,5\)
c, \(\dfrac{8.5^2-8.4^2}{2^2.3^2}=\dfrac{8.\left(5^2-4^2\right)}{2^2.3^2}=\dfrac{8.9}{4.9}=2\)
d, \(\dfrac{7^4.2^2+7^4.3}{49.26}=\dfrac{7^4.\left(2^2+3\right)}{7^2.26}=\dfrac{7^4.7}{7^2.26}=\dfrac{343}{26}\)
Have a nice day!
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`a) (2^5 .3^2)/(2^3 .3)`
`= (2^2 .3)/1`
`= 4.3`
`=12`
`b) (5^3 .6)/(5.2^2)`
`= (5^3 .2.3)/(5.2^2)`
`= (5^2 .3)/2`
`= 75/2`
`c) (8.5^2-8.4^2)/(2^2 .3^2)`
`= (8.(5^2-4^2))/(4.9)`
`= (8.9)/(4.9)`
`= (2.4.9)/(4.9)`
`=2`
`d) (7^4 .2^2+7^4 .3)/(49.26)`
`= (7^4.(2^2+3))/(7^2 .26)`
`= (7^4 .7)/(7^2 .26)`
`= (7^5)/(7^2. 26)`
`= (7^3)/26`
`= 343/26`
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Ta có:a,49×101=4949
b,89×1998=89×(2000-2)
=89×2000-89×2=177822
c,34×2002=34×(1001×2)=68068
d,105×16=105×(17-1)=1680
e,99×101=9999
ks nhé+Học tốt!:))
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Tính B = 1 + 2+ 3+ ...+ 98+99B = 1 + (2 + 3 + 4+...+ 98 + 99).
Ta thấy tổng trong ngoặc gồm 98 số hạng, nếu chia thành các cặp ta có 49 cặp nên tổng đó là:
(2 + 99) + (3 + 98) +..+ (51 + 50) = 49.101 = 4949
khi đó B = 1 + 4949 = 4950
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a) 17.88 + 17.12
= 17. (88 + 12)
= 17.100
= 1 700.
b) 25.32 + 4.92.25
= 25.(32 + 4.92)
= 25.(32 + 368)
= 25.400
= 10 000.
c) 3 119.121 - 3 119.11.11
= 3 119.121 - 3 119.121
= 3 119(121 – 121)
= 3 119.0
= 0.
d) 24.(123 + 87) + (87 + 123).76
= 24.210 + 210.76
= 210.(24 + 76)
= 210. 100
= 21 000.
\(25\cdot32=25\cdot4\cdot8\)
\(=\left(25\cdot4\right)\cdot8=100\cdot8\)
\(=800\)
\(49\cdot101=49\cdot\left(100+1\right)\)
\(=49\cdot100+49\)
\(=4900+49\)
\(=4949\)