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a, \(\left(4x+5\right)^2=\left(4x+5\right)\left(4x+5\right)=\left[\left(4x+5\right)4x\right]+\left[\left(4x+5\right)5\right]=4x^2+20x+25\)
b, \(\left(5x-2\right)^2=\left(5x-2\right)\left(5x-2\right)=\left[\left(5x-2\right)5x-\left(5x-2\right)2\right]=5x^2-10x+25\)
b, \(8^2-12x^2=\left(8^2-12x^2\right)\left(8^2+12x^2\right)\)
đúng ko :)
@No name: Bị sai rồi nhé, a,b,c sai hết :>
a) ( 4x + 5 )2
= ( 4x )2 + 2.4x.5 + 52
= 16x2 + 40x + 25
b) ( 5x - 2 )2
= ( 5x )2 - 2.5x.2 + 22
= 25x2 - 20x + 4
c) 82 - 12x2
= 64 - 12x2
= ( V8 - V12x )( V8 + V12x )
( 3x+2). (3x-2)+(x-3)2-10x
=9x2-4+x2-6x+9-10x
=9x2-4+x2-6x+9
=10x-16x+5
(2x+y)2+ (x-2y)2-5. (x+y).(x-y)
=4x2+4xy+y2+x2-4xy+4y2-5.(x2-y2)
=4x2+4xy+y2+x2-4xy+4y2-5x2+5y2
=10y2
(3x-5)2- x.(3x-5)
=9x2-30x+25-3x2+15
=6x2-30x+40
Bài làm:
a) \(\left(x^4-2x^2y+y^2\right)\div\left(y-x^2\right)\)
\(=\left(x^2-y\right)^2\div\left(y-x^2\right)\)
\(=\left(y-x^2\right)^2\div\left(y-x^2\right)\)
\(=y-x^2\)
b) \(\left(x^2-2xy^2+y^4\right)\div\left(x-y^2\right)\)
\(=\left(x-y^2\right)^2\div\left(x-y^2\right)\)
\(=x-y^2\)
bài 1: a) \(x^2-3=x^2-\left(\sqrt{3}\right)^2=\left(x+\sqrt{3}\right)\left(x-\sqrt{3}\right)\)
b) \(\left(a+b\right)^2-\left(a+b\right)^2=\left(a+b+a+b\right)\left(a+b-a-b\right)=2a+2b=2\left(a+b\right)\)
c) \(x^3-27b^3=\left(x-3b\right)\left(x^2+3xb+b^2\right)\)
Bài 1:
a, \(x^2+10x+26+y^2+2y\)
\(=x^2+2.x.5+5^2+y^2+2.y.1+1^2\)
\(=\left(x+5\right)^2+\left(y+1\right)^2\)
b, \(x^2-2xy+2y^2+2y+1\)
\(=x^2-2.x.y+y^2+y^2+2.y.1+1^2\)
\(=\left(x-y\right)^2+\left(y+1\right)^2\)
c, \(4x^2+2z^2-4xz-2z+1\)
\(=\left(2x\right)^2-2.2x.z+z^2+z^2-2.z.1+1^2\)
\(=\left(2x-z\right)^2+\left(z-1\right)^2\)
Chúc bạn học tốt!!!
Bài1:
Bn kia giải r nhé
Bài 2:
a)\(127^2+146.127+73^2=127^2+2.73.127+73^2\)
=\(\left(127+73\right)^2=200^2=40000\)
b)\(31,8^2-63,6.21,8+21,8^2=\left(31,8-21,8\right)^2=10^2=100\)
c)\(2018^2-2017^2+2016^2-2015^2+...+2^2-1\)
=\(\left(2018+2017\right)+\left(2015+2016\right)+...+\left(2+1\right)\)
=4025+4031+...+3
=...(bn tự tính)
d)\(2017^2-2016.2018=2017^2-\left(2017^2-1\right)=1\)