127² + 146.127 + 73²

= 127² + 2 . 73 .127 + 73²

= (127 + 73 ) ²

= 200 ²

a) \(127^2+146.127+73^2=127^2+2.73.127+73^2=\left(127+73\right)^2=40000\)b) \(9^8.2^8-\left(18^4-1\right)\left(18^4+1\right)=18^8-\left(18^8-1\right)=1\)

c) \(100^2-99^2+98^2-97^2+...+2^2-1^2\)

\(=\left(100-99\right)\left(100+99\right)+\left(98-97\right)\left(98+97\right)+...+\left(2-1\right)\left(2+1\right)\)\(=100+99+98+97+...+2+1\)

\(=\dfrac{100\left(100+1\right)}{2}=5050\)

d) \(\left(20^2+18^2+16^2+...+4^2+2^2\right)-\left(19^2+17^2+15^2+...+3^2+1^2\right)\) \(=20^2-19^2+18^2-17^2+16^2-15^2+...+4^2-3^2+2^2-1^2\)

\(=\left(20-19\right)\left(20+19\right)+\left(18-17\right)\left(18+17\right)+...+\left(2-1\right)\left(2+1\right)\)\(=20+19+18+17+...+2+1\)

\(=\dfrac{20\left(20+1\right)}{2}=210\)

e) \(\dfrac{780^2-220^2}{125^2+150.125+75^2}\)

\(=\dfrac{\left(780-220\right)\left(780+220\right)}{\left(125+75\right)^2}=\dfrac{560.1000}{200}=2800\)

a/ A = 100² - 99² + 98² -...+2² - 1²

= (100² - 99²) + (98² - 97²) +...+ (2² - 1²)

= 199 + 195 + 191 + ... + 1

= (\(\frac{199-1}{4}+1\))(\(\frac{199+1}{2}\)) = 5050

b/ Y chang câu a luôn nha

c/ \(C=\frac{780^2-220^2}{125^2+150.125+75^2}=\frac{\left(780-220\right)\left(780+220\right)}{\left(125+75\right)^2}\)

\(=\frac{560.1000}{200^2}=14\)

d/ 2(a + 4)(a + 5) - (a + 5)² - (a² - 9a - 17) 

= 17a + 32 = 17(a + 1) + 15 = 1700 + 15 = 1715

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

 \(\text{c)}\frac{780^2-220^2}{125^2+150\cdot125+75^2}\)

\(=\frac{\left(780-220\right)\left(780+220\right)}{125^2+2\cdot75\cdot125+75^2}\)

\(=\frac{560\cdot1000}{\left(125+75\right)^2}\)

\(=\frac{560000}{200^2}\)

\(=\frac{560000}{40000}\)

\(=14\)

a. 134^2 - 68.134 + 34^2 = ( 134 - 34 ) ^2 = 100^2 = 10000

b. 9^8.2^8 - ( 18^4 - 1 )(18^4 + 1 ) = 18^8 - 18^8 + 1 = 1

c. 100^2 - 99^2 + 98^2 - 97^2 + ... + 2^2 - 1 

=( 100 - 99 )( 100 + 99 ) + ( 98 - 97 )( 98 + 97 ) + ... + ( 2 - 1 )( 2 + 1 )

= 100 + 99 + 98 + 97 + ... + 2 + 1

=( 100 + 1 ).100:2 = 5050

\(A=\left(100^2-99^2\right)+\left(98^2-97^2\right)+...+\left(2^2-1^2\right)\)

\(=\left(100-99\right)\left(100+99\right)+\left(98-97\right)\left(98+97\right)+...+\left(2-1\right)\left(2+1\right)\)

\(=100+99+98+97+...+2+1\)

\(=\left(100+1\right).\frac{100-1}{2}=\frac{101.99}{2}=\frac{9999}{2}\)

Bài 11:

1) Sửa lại đề là: \(A=127^2+146.127+73^2\)

\(\Rightarrow A=127^2+2.127.73+73^2\)

\(\Rightarrow A=\left(127+73\right)^2\)

\(\Rightarrow A=200^2\)

\(\Rightarrow A=40000\)

Vậy \(A=40000.\)

2) Sửa lại đề là: \(B=9^8.2^8-\left(18^4-1\right).\left(18^4+1\right)\)

\(\Rightarrow B=\left(9.2\right)^8-\left[\left(18^4\right)^2-1^2\right]\)

\(\Rightarrow B=18^8-\left(18^8-1\right)\)

\(\Rightarrow B=18^8-18^8+1\)

\(\Rightarrow B=0+1\)

\(\Rightarrow B=1\)

Vậy \(B=1.\)

4) \(D=\left(3+1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

\(\Rightarrow2D=\left(3-1\right).\left(3+1\right).\left(3^2+1\right).\left(3^4+1\right).\left(3^8+1\right).\left(3^{16}+1\right)\)

\(=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)

\(=\left(3^{16}-1\right)\left(3^{16}+1\right)\)

\(=3^{32}-1\)

\(\Rightarrow D=\frac{3^{32}-1}{2}\)

MẤY BẠN GIÚP MÌNH VỚI MÌNH CẦN GẤP LẮM

A = 1995² - ( 1995-1) (1995+1)

= 1995² - (1995² - 1²)

= 1995² - 1995² +1

= 1

A = - tại x = 1.856; y = -0,988

B = : tại x = 2003 ; y= 2004

A= chắc sai đề

B= :

=(x-y)(x+y)

thay số =(2003-2004)(2003+2004)=-4007

2

phần a chắc lại có vấn đề

B=(780^2-220^2)/125^2+150.125+75^2

=(780-220)(780+220)/(125+75)^2

=560.1000/200^2

7/5

c=100² - 99² + 98² - 97² +....+ 2² - 1

=(100-99)(100+99)........(2+1)(2-1)

=100+99+...+1

=5050