Tính nhanh
C) 127^2 +146+127+732
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\(c,=\left(100-7\right)\left(100+7\right)=10000-49=9951\\ d,=127^2+2\cdot73\cdot127+73^2=\left(127+73\right)^2=200^2=40000\)
a) \(=\left(127+73\right)^2=200^2=40000\)
b) \(=18^8-\left(18^8-1\right)=1\)
c) \(=\left(100+99\right)\left(100-99\right)+\left(98+97\right)\left(98-97\right)+...+\left(2+1\right)\left(2-1\right)\)
\(=100+99+98+97+...+2+1=5050\)
d) biến đổi thành \(20^2-19^2+18^2-17^2+..+2^2-1^2\)
rồi giải ra như trên
Answer:
\(A=127^2+146.127+73^2\)
\(=127^2+2.127.73+73^2\)
\(=\left(127+73\right)^2\)
\(=200^2\)
\(=40000\)
\(B=9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)\)
\(=\left(9.2\right)^8-[\left(18^4\right)^2-1]\)
\(=18^8-18^8+1\)
\(=1\)
\(C=\left(20^2+18^2+16^2+...+4^2+2^2\right)-\left(19^2+17^2+15^2+...+3^2+1^2\right)\)
\(=20^2+18^2+16^2+...+4^2+2^2-19^2-17^2-15^2-...-3^2-1^2\)
\(=\left(20^2-19^2\right)+\left(18^2-17^2\right)+...+\left(2^2-1^2\right)\)
\(=\left(20-19\right)\left(20+19\right)+\left(18-17\right)\left(18+17\right)+...+\left(2-1\right)+\left(2+1\right)\)
\(=1.39+1.35+...+1.3\)
\(=39+35+...+3\)
Số số hạng \(\frac{39-3}{4}+1=10\) số hạng
Tổng \(\frac{\left(39+3\right).10}{2}=210\)
a, \(C=127^2+146.127+73^2\)
\(=127^2+2.127.73+73^2\)
\(=\left(127+73\right)^2\)
\(=200^2=40000\)
a, \(\frac{2006^3+1}{2006^2-2005}\)
\(=\frac{\left(2006+1\right)\left(2006^2-2006+1\right)}{2006^2-2005}=\frac{2007\left(2006^2-2005\right)}{2006^2-2005}=2007\)
\(\frac{2006^3-1}{2006^2+2007}\)
\(=\frac{\left(2006-1\right)\left(2006^2+2006+1\right)}{2006^2+2007}=\frac{2005\left(2006^2+2007\right)}{2006^2+2007}=2005\)
Chúc bạn học tốt.
a) 1272 + 146.127 + 732
= 1272 + 2.73.127 + 732
= (127 + 73)2 = 2002 = 40000
b) 98 . 28 - (184 - 1)(184 + 1)
= (9.2)8 - 188 + 1
= 188 - 188 + 1 = 1
c) \(\frac{780^2-220^2}{125^2+150.125+75^2}=\frac{\left(780-220\right)\left(780+220\right)}{125^2+2.75.125+75^2}=\frac{560.1000}{\left(125+75\right)^2}=\frac{560000}{200^2}\)
\(=\frac{560000}{40000}=14\)
a) 1272 + 146.127 + 732
= 1272 + 2.73.127 + 732
= ( 127 + 73 )2
= 2002 = 40 000
b) 98.28 - ( 184 - 1 )( 184 + 1 )
= ( 9.2 )8 - [ ( 184 )2 - 12 ]
= 188 - 188 + 1
= 1
c) \(\frac{780^2-220^2}{125^2+150\cdot125+75^2}\)
\(=\frac{\left(780-220\right)\left(780+220\right)}{125^2+2\cdot75\cdot125+75^2}\)
\(=\frac{560\cdot1000}{\left(125+75\right)^2}\)
\(=\frac{560000}{200^2}\)
\(=\frac{560000}{40000}=14\)
a/ \(127^2+146\cdot127+73^2=127^2+2\cdot73\cdot127+73^2=\left(127+73\right)^2=200^2=40000\)
b/ \(100^2-99^2+98^2-97^2+...+2^2-1^2=\left(100^2-99^2\right)+\left(98^2-97^2\right)+...+\left(2^2-1^2\right)\)
\(=100+99+98+97+...+2+1=\frac{\left(100\right)\left(100+1\right)}{2}=5050\)
c/ \(34^2+66^2+68\cdot66=34^2+66^2+2\cdot34\cdot66=\left(34+66\right)^2=100^2=10000\)
127^2+146+127+732
=16129+146+127+732
=17134
Tính nhanh
C) 127^2 +146+127+732
= 127.127+127+19+127+127.5+97
= 127.134+19+81+16
= 17018+100+16
= 17134