Tính nhanh:
a) 34^2 + 66^2 + 68.66
b) 74^2 + 24^2 - 48 . 74
c) 729^2 - 728^2
d) 1001^2 - 1
làm dùm nha
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MV
16 tháng 7 2017
4)
a,
\(34^2+66^2+68\cdot66\\ =34^2+68\cdot66+66^2\\=34^2+2\cdot34\cdot68+66^2\\ =\left(34+66\right)^2\\ =100^2 =10000\)
b,
\(74^2+24^2-48\cdot74\\ =74^2-48\cdot74+24^2\\ =74^2-2\cdot24\cdot74+24^2\\ =\left(74-24\right)^2\\ =50^2=2500\)
c,
\(729^2-728^2\\ =\left(729+728\right)\left(729-728\right)\\ =1457\cdot1\\ =1457\)
d,
\(1001^2-1\\ =1001^2-1^2\\ =\left(1001+1\right)\left(1001-1\right)\\ =1002\cdot1000\\ =1002000\)
5)
a,
\(\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =1\cdot\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =\left(2^8-1\right)\left(2^8+1\right)\\ =2^{16}-1\)
b,
\(7\cdot\left(2^3+1\right)\left(2^6+1\right)\left(2^{12}+1\right)\left(2^{24}+1\right)\\ =\left(2^3-1\right)\left(2^3+1\right)\left(2^6+1\right)\left(2^{12}+1\right)\left(2^{24}+1\right)\\ =\left(2^6-1\right)\left(2^6+1\right)\left(2^{12}+1\right)\left(2^{24}+1\right)\\ =\left(2^{12}-1\right)\left(2^{12}+1\right)\left(2^{24}+1\right)\\ =\left(2^{24}-1\right)\left(2^{24}+1\right)\\ =2^{48}-1\)
NQ
2
28 tháng 8 2016
a. 34^2 + 66^2 + 68 x 66
= 34 x 34 + 66 x 66 + 68 x 66
= 34 x 34 + 66 x (66 + 68)
= 34 x 34 + 66 x 134
= 34 x 34 + 66 x 34 + 66 x 100
= 34 x (34 + 66) + 66 x 100
= 34 x 100 + 66 x 100
= (34 + 66) x 100
= 100 x 100
= 10000
30 tháng 8 2016
\(34^2+66^2+68.66\)
\(=34.34+66.66+68.66\)
\(=34.34+66.\left(68+66\right)\)
\(=34.34+66.134\)
\(=34.34+66.\left(100+34\right)\)
\(=34.34+66.100+66.34\)
\(=34.\left(66+34\right)+66.100\)
\(=34.100+66.100\)
\(=\left(34+66\right).100\)
\(=100^2\)
\(=10000\)
NT
6
6 tháng 1 2018
( 34^2+66^2+68.66
= 34^2 + 66^2 + 2. 34.66
= ( 34+66)^2
= 100^2 = 10 000
b) 74^2 + 24^2 - 48.74
= 74^2 + 24^2 - 2. 74 . 24
= (74-24)^2 = 50^2 = 2500
MC
6 tháng 1 2018
a) 34^2 + 66^2 + 68 . 66 = 5580,66
b) 74^2 + 24^2 – 48 . 74 = 6003.26
TH
0
RN
2
MT
24 tháng 6 2015
a/ 34^2 + 66^2 + 68 . 66
=342+2.34.66+662
=(34+66)2
=1002
=10000
b/ 74^2 + 24^2 - 48 . 74
=742-2.74.24+242
=(74-24)2
=502
=2500
12 tháng 9 2016
\(a,34^2+66^2+68.66\)
\(=34^2+2.34.66+66^2\)
\(=\left(34+66\right)^2\)
\(=100^2\)
\(=10000\)
\(b,74^2+24^2-48.74\)
\(=74^2-2.74.24+24^2\)
\(=\left(74-24\right)^2\)
\(=50^2\)
\(=2500\)
XN
1
27 tháng 9 2017
a) \(34^2+66^2+68.66\)
\(=34^2+2.34.66+66^2\)
\(=\left(34+66\right)^2\)
\(=100^2=10000\)
b) \(74^2+24^2-48.74\)
\(=74^2-2.74.24+24^2\)
\(=\left(74-24\right)^2\)
\(=50^2=2500\)
CM
0
28 tháng 6 2021
`a)1001^2`
`=(1000+1)^2=1000000+2000+1`
`=1002001`
`b)29,9.30,1`
`=(30-0,1)(30+0,1)`
`=30^2-0,1^2`
`=900-0,01=899,99`
`c)199^2=(200-1)^2`
`=40000-400+1`
`=39601`
`d)84^2-16^2`
`=(84-16)(84+16)`
`=100.68`
`=6800`
`e)313^2-312^2`
`=(313-312)(313+312)`
`=625`
`f)47.53`
`=(50-3)(50+3)`
`=2500-9=2491`
a) \(=34^2+66^2+2.34.66=\left(34+66\right)^2=100^2=10000\)
b) \(=74^2+24^2-2.24.74=\left(74-24\right)^2=2500\)
c) \(=\left(729-728\right)\left(729+728\right)=1.1457=1457\)
d) \(=\left(1001-1\right)\left(1001+1\right)=1000.1002=1002000\)
Chúc bạn học tốt.
rút gn
a) (2-1)(2^2-1)(2^4+1)(2^8+1)