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a, 100 - ( 3. 52 - 2 . 32 )
= 100 - 3.( 52 - 6 )
= 100 - 3 .19
= 100 - 57
=43
b, 2665: [ 213 - ( 17 - 32 ) ] + 347 . 52
= 2665 : [213 - 8 ] + 8675
= 13 + 8675
=8688
1,100-(3.5\(^2\)-2.3\(^2\))
=100-(3.25-2.9)
=100-(75-18)
=100-57
=43
2,2665:\([\)213-(17-3\(^2\))\(]\)+347.5\(^2\)
=2665:\([\)213-8\(]\)+8675
=2665:205+8675
=13+8675
=8688
100 - (3 . \(5^2-2.3^3\) )
= 100 - ( 3. \(5^2-2.3^3\) )
= 100 - ( 3 . 25 - 2 . 27 )
= 100 - ( 75 - 54 )
= 100 - 21
= 79
100-(3.52-2.33)
=100-(75-54)
=100-21
=79
Chúc Yến Nhi học tốt!
Bài giải
\(B=1\cdot2^2+2\cdot3^2+3\cdot4^2+...+99\cdot100^2\)
\(B=1\cdot2\cdot\left(3-1\right)+2\cdot3\cdot\left(4-1\right)+3\cdot4\cdot\left(5-1\right)+...+99\cdot100\cdot\left(101-1\right)\)
\(B=1\cdot2\cdot3-1\cdot2+2\cdot3\cdot4-2\cdot3+...+99\cdot100\cdot101-99\cdot100\)
\(B=\left(1\cdot2\cdot3+2\cdot3\cdot4+...+99\cdot100\cdot101\right)-\left(1\cdot2+2\cdot3+...+99\cdot100\right)\)
Đặt \(C=1\cdot2\cdot3+2\cdot3\cdot4+...+99\cdot100\cdot101\)
\(4C=1\cdot2\cdot3\cdot4+2\cdot3\cdot4\cdot\left(5-1\right)+...+99\cdot100\cdot101\cdot\left(102-98\right)\)
\(4C=1\cdot2\cdot3\cdot4+2\cdot3\cdot4\cdot5-1\cdot2\cdot3\cdot4+...+99\cdot100\cdot101\cdot102-98\cdot99\cdot100\cdot101\)
\(4C=99\cdot100\cdot101\cdot102\)
\(4C=101989800\)
\(C=101989800\text{ : }4\)
\(C=25497450\)
\(100-\left(3.5^2-2.3^3\right)\)
\(=100-\left(125-54\right)\)
=\(100-71=29\)
Gọi A là biểu thức ta có:
CÂU1 :A = 1.2+2.3+3.4+......+99.100
3A = 1.2.3 + 2.3.3 + 3.4.3 + … + 99.100.3
3A = 1.2.3 + 2.3.(4 - 1) + 3.4.( 5 - 2) + … + 99.100. (101 - 98)
3A = 1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + … + 99.100.101 - 98.99.100
3A = 99.100.101
A = 99.100.101 : 3
A = 33.100.101
A = 333 300
a) 32-6.(8-23)+18
= 32 - 6 . (8 - 8) +18
=32 - 0 +18
= 50
b) (3.5-9)3.(1+2.3)2+42
= (15-9 )3. (1+6)2 + 4 2
= 63 . 7 2 + 42
= 216 x 49 + 16
= 10584 + 16
=10600
c) 9234:[3.3.(1+83)]
= 9234 : [ 3.3.93]
= 9234 : [ 3.3 . 729]
= 9234 :6561
= 1,407407407
d) 76- {2.[2.52-(31-2.3)]}+3.25
= 76 - { 2. [ 2.52 - ( 31 - 6)]} + 3.25
= 76 - { 2 . [ 2. 52 - 25 ]} + 3 .25
= 76 - { 2 . [2. 25 - 25]} + 3.25
= 76 - { 2.[ 50 - 25 ]} + 3.25
= 76 - { 2. 25} + 3 . 25
= 76 - 50 + 3. 25
= 76 - 50 + 75
= 101
1) \(100-\left(3.5^2-2.3^2\right)\)
\(=100-\left(3.25-2.9\right)\)
\(=100-\left(75-18\right)\)
\(=100-57\)
\(=43\)
2) \(2665:\left[213-\left(17-3^2\right)\right]+347.5^2\)
\(=2665:\left[213-\left(17-9\right)\right]+347.25\)
\(=2665:\left[213-8\right]+8675\)
\(=2665:205+8675\)
\(=13+8675\)
\(=8688\)