Tính nhanh :
a) 1272+146.127+732
b) 98.28-(184-1)(184+1)
c) \(\frac{180^2-220^2}{125^2+150.125+75^2}\)
Những câu hỏi liên quan
tính nhanh
a)1272+146.127+732
b)98.28-(184-1)(184+1)
c)1802-2202/1252+150.125+752
Tinh nhanh
a)1272+146*127+732
b)98*28-(184-1)(184+1)
c)1002-992+982-972+...+22-12
d)(180^2-220^2)/125^2+150*125+75^2
Tính Nhanh:
\(B=\frac{780^2-220^2}{125^2+150.125+75^2}\)
\(B=\frac{780^2-220^2}{125^2+150.125+75^2}\)\(=\frac{\left(780+220\right).\left(780-220\right)}{\left(125+75\right)^2}\)\(=\frac{1000.560}{200^2}\)\(=\frac{560000}{40000}=14\)
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Tính nhanh :
A=100^2+98^2+96^2+....+2^2 - 99^2-97^2-95^2-....-1^2
B= 780^2-220^2/125^2+75^2+150.125
\(A=\left(100^2-99^2\right)+\left(98^2-97^2\right)+...+\left(2^2-1^2\right)\)
\(=\left(100-99\right)\left(100+99\right)+\left(98-97\right)\left(98+97\right)+...+\left(2-1\right)\left(2+1\right)\)
\(=100+99+98+97+...+2+1\)
\(=\left(100+1\right).\frac{100-1}{2}=\frac{101.99}{2}=\frac{9999}{2}\)
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Tính nhanh, dùng hằng đẳng thức thứ 1;2;3
a) 1272 + 146 . 127 + 732
b) 98 . 28 - (184 - 1)(184 + 1)
c) \(\frac{780^2-220^2}{125^2+150.125+75^2}\)
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) \(\frac{780^2-220^2}{125^2+150\cdot125+75^2}\)
\(=\frac{\left(780-220\right)\left(780+220\right)}{125^2+2\cdot75\cdot125+75^2}\)
\(=\frac{560\cdot1000}{\left(125+75\right)^2}\)
\(=\frac{560000}{200^2}\)
\(=\frac{560000}{40000}=14\)
Bài làm :
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
\(\text{c)}\frac{780^2-220^2}{125^2+150\cdot125+75^2}\)
\(=\frac{\left(780-220\right)\left(780+220\right)}{125^2+2\cdot75\cdot125+75^2}\)
\(=\frac{560\cdot1000}{\left(125+75\right)^2}\)
\(=\frac{560000}{200^2}\)
\(=\frac{560000}{40000}\)
\(=14\)
Bài 1:
a) 1042 - 16
b) 98.28 - (184 - 1)(184 + 1)
c) 9993 +3.9992 + 3.999 + 1
d) 423 - 6.422 + 12.42 - 8
Bài 2:
a) x(x - 2012) - 2013x +2012.2013 = 0
b) (x - 1)3 + 1 + 3x(x - 4) = 0
c) (x + 4)2 - 16 = 0
\(Bài.1:\\ a,104^2-16=104^2-4^2=\left(104+4\right)\left(104-4\right)=108.100=10800\\ b,9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)\\ =\left(9.2\right)^8-\left(18^8-1\right)=18^8-18^8+1=1\\ c,999^3+3.999^2+3.999+1\\ =999^3+3.999^2.1+3.999.1^2+1^3=\left(999+1\right)^3=1000^3=1000000000\\ d,42^3-6.42^2+12.42-8\\ =42^3-3.42^2.2+3.42.2^2-2^3\\ =\left(42-2\right)^3=40^3=64000\)
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Bài 1
a) 104² - 16
= 104² - 4²
= (104 - 4)(104 + 4)
= 100.108
= 10800
b) 9⁸.2⁸ - (18⁴ - 1)(18⁴ + 1)
= 18⁸ - (18⁸ - 1)
= 18⁸ - 18⁸ + 1
= 1
c) 999³ + 3.999² + 3.999 + 1
= (999 + 1)³
= 1000³
= 1000000000
d) 42³ - 6.42² + 12.42 - 8
= (42 - 2)³
= 40³
= 64000
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Bài 2
a) x(x - 2012) - 2013x + 2012.2013 = 0
⇔ x(x - 2012) - 2013(x - 2012) = 0
⇔ (x - 2012)(x - 2013) = 0
⇔ x - 2012 = 0 hoặc x - 2013 = 0
*) x - 2012 = 0
⇔ x = 2012
*) x - 2013 = 0
⇔ x = 2013
Vậy x = 2012; x = 2013
b) (x - 1)³ + 1 + 3x(x - 4) = 0
⇔ x³ - 3x² + 3x - 1 + 1 + 3x² - 12x = 0
⇔ x³ - 9x = 0
⇔ x(x² - 9) = 0
⇔ x(x - 3)(x + 3) = 0
⇔ x = 0 hoặc x - 3 = 0 hoặc x + 3 = 0
*) x - 3 = 0
⇔ x = 3
*) x + 3 = 0
⇔ x = -3
Vậy x = -3; x = 0; x = 3
c) (x + 4)² - 16 = 0
⇔ (x + 4)² - 4² = 0
⇔ (x + 4 - 4)(x + 4 + 4) = 0x
⇔ (x + 8) = 0
⇔ x = 0 hoặc x + 8 = 0
*) x + 8 = 0
⇔ x = -8
Vậy x = -8; x = 0
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Tính nhanh :
a) ( 202 + 182 + 162 + ... + 42 ) - ( 192 + 172 + 152+ ... + 12 )
b) \(\frac{780^2-220^2}{125^2+150.125+75^2}\)
Tính nhanh
a) 1272 + 146x127 + 732
b) 98x28 - (184-1)x(184+1)
\(\left(780^2-220^2\right):\left(125^2+150.125+75^2\right)\)
\(\left(780^2-220^2\right):\left(125^2+150\cdot125+75^2\right)\)
\(=\dfrac{1000\cdot540}{200^2}\)
\(=\dfrac{10000\cdot54}{40000}=\dfrac{54}{4}=\dfrac{27}{2}\)
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