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19 tháng 8 2021

c) \(\left(x^2-y^2\right)^2=x^4-2x^2y^2+y^4\)

c) \(\left(x^2+3^2\right)^2=x^4+18x+81\)

c) \(\left(2x^2+1\right)^2=4x^4+4x^2+1\)

c) \(\left(3x-y^2\right)^2=9x^2-6xy^2+y^4\)

c) \(\left(x+2y^2\right)^2=x^2+4xy^2+4y^4\)

c) \(\left(3x\right)^2-y^2=\left(3x-y\right)\left(3x+y\right)\)

c) \(\left(2x+3y^2\right)^2=4x^2+12xy^2+9y^4\)

c) \(\left(4x-2y^2\right)^2=16x^2-16xy^2+4y^4\)

c) \(\left(4x^2-2y\right)^2=16x^4-16x^2y+4y^2\)

19 tháng 8 2021

c) \(\left(\dfrac{1}{x}-5\right)\left(\dfrac{1}{x}+5\right)=\dfrac{1}{x^2}-25\)

c) \(\left(x-\dfrac{3}{2}\right)\left(x+\dfrac{3}{2}\right)=x^2-\dfrac{9}{4}\)

c) \(\left(\dfrac{x}{3}-\dfrac{y}{4}\right)\left(\dfrac{x}{3}+\dfrac{y}{4}\right)=\dfrac{x^2}{9}-\dfrac{y^2}{16}\)

c) \(\left(\dfrac{x}{y}-\dfrac{2}{3}\right)\left(\dfrac{x}{y}+\dfrac{2}{3}\right)=\dfrac{x^2}{y^2}-\dfrac{4}{9}\)

c) \(\left(\dfrac{x}{2}+\dfrac{y}{3}\right)\left(\dfrac{y}{3}-\dfrac{x}{2}\right)=\dfrac{y^2}{9}-\dfrac{x^2}{4}\)

c) \(\left(2x-\dfrac{2}{3}\right)\left(\dfrac{2}{3}+2x\right)=4x^2-\dfrac{4}{9}\)

c) \(\left(2x+\dfrac{3}{5}\right)\left(\dfrac{3}{5}-2x\right)=\dfrac{9}{25}-4x^2\)

c) \(\left(\dfrac{1}{2}x-\dfrac{4}{3}\right)\left(\dfrac{4}{4}+\dfrac{1}{2}x\right)=\dfrac{1}{4}x^2-\dfrac{16}{9}\)

c) \(\left(\dfrac{2}{3}x^2-\dfrac{y}{2}\right)\left(\dfrac{2}{3}x^2+\dfrac{y}{2}\right)=\dfrac{4}{9}x^4-\dfrac{y^2}{4}\)

(x2 + 32)

=x^4 + 18x^2+81

6 tháng 7 2021

(x2 + 32)2 

= (x2)2 + 2x2 . 32 + (32)2 

= x4 + 18x2 + 81

 

\(4x^4-4x^2+1=\left(2x^2-1\right)^2\)

\(\left(x+2y\right)^2=x^2+4xy+4y^2\)

\(36-12x+x^2=\left(6-x\right)^2\)

\(\left(x+5y\right)^2=x^2+10xy+25y^2\)

\(4x^2-12x+9=\left(2x-3\right)^2\)

\(\left(x-2y\right)^2=x^2-4xy+4y^2\)

2 tháng 7 2021

( 2x - 3y )2 = 4x2 - 12xy + 9y2

( 3√x - y )2 = 9x - 6y√x + y2 ( x ≥ 0 )

21 tháng 6 2016

4x^2 - 7x -2 = 4x^2 - 8x + x - 2 = 4x(x - 2) + (x - 2) = (x -2)(4x + 1)

21 tháng 6 2016

\(4x^2-7x-2=4x^2-8x+x-2=4x\left(x-2\right)+\left(x-2\right)=\left(x-2\right)\left(4x+1\right)\)

6 tháng 7 2021

a/ \(36+x^2-12x=x^2-2x.6+6^2=\left(x+6\right)^2\)

b/ \(\left(x+2y\right)^2=x^2+2x.2y+\left(2y\right)^2=x^2+4xy+4y^2\)

c/ \(\left(\sqrt{x}-2\sqrt{y}\right)^2=\left(\sqrt{x}\right)^2-2\sqrt{x}.2\sqrt{y}+\left(2\sqrt{y}\right)^2=x-4\sqrt{xy}+4y\)

16 tháng 9 2021

\(a,=x^2+x+\dfrac{1}{4}\\ b,=4x^2+2x+\dfrac{1}{4}\\ c,=x^2-2+\dfrac{1}{x^2}\\ d,=4x^2+\dfrac{8}{3}x+\dfrac{4}{9}x^2\\ e,=a^2-1\\ f,=25x^4-4\)

16 tháng 9 2021

\(a,\left(x+\dfrac{1}{2}\right)^2=x^2+x+\dfrac{1}{4}\)

\(b,\left(2x+\dfrac{1}{2}\right)^2=4x^2+2x+\dfrac{1}{4}\)

\(c,\left(x-\dfrac{1}{x}\right)^2=x^2-2+\dfrac{1}{x^2}\)

\(d,\left(\dfrac{2x+2}{3x}\right)^2=\dfrac{\left(2x+2\right)^2}{9x^2}=\dfrac{4x^2+8x+4}{9x^2}\)

\(e,\left(a-1\right).\left(a+1\right)=a^2-1\)

\(f,\left(5x^2-2\right).\left(5x^2+2\right)=25x^4-4\)

11 tháng 9 2017

(a+b)3-(a-b)3=a3+3a2b+3ab2+b3-(a3-3a2b+3ab2-b3)

                    =a3+3a2b+3ab2+b3-a3+3a2b-3ab2+b3

                        =6a2b+2b3

11 tháng 9 2017

Áp dụng hđt a3-b3=(a-b)(a2+ab+b2) ấy

\(\left(a+b\right)^3-\left(a-b\right)^3=\left[\left(a+b\right)-\left(a-b\right)\right]\left[\left(a+b\right)^2+\left(a+b\right)\left(a-b\right)+\left(a-b\right)^2\right]\)

\(=\left(a+b-a+b\right)\left(a^2+2ab+b^2+a^2-b^2+a^2-2ab+b^2\right)\)

\(=2b\left(3a^2+b^2\right)\)

25 tháng 8 2021

\(\left(x-y\right)^3-x^3+y^3=\left(x-y\right)^3-\left(x^3-y^3\right)=\left(x-y\right)^3-\left(x-y\right)\left(x^2+xy+y^2\right)=\left(x-y\right)\left(x^2-2xy+y^2-x^2-xy-y^2\right)=-3xy\left(x-y\right)\)

25 tháng 8 2021

\(\left(x-y\right)^3-x^3+y^3\\ =\left(x-y\right)^3-\left(x^3-y^3\right)\\ =\left(x-y\right)^3-\left(x-y\right)\left(x^2+xy+y^2\right)\\ =\left(x-y\right)\left[\left(x-y\right)^2-\left(x^2+xy+y^2\right)\right]\\ =\left(x-y\right)\left(x^2-2xy+y^2-x^2-xy-y^2\right)\\ =\left(-3xy\right)\left(x-y\right)\)