Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
( 2x - 3y )2 = 4x2 - 12xy + 9y2
( 3√x - y )2 = 9x - 6y√x + y2 ( x ≥ 0 )
a, \(\left(\frac{x}{y}-\frac{2}{3}\right)\left(\frac{x}{y}+\frac{2}{3}\right)=\left(\frac{x}{y}\right)^2-\left(\frac{2}{3}\right)^2\)
b,\(\left(2\sqrt{x}-\frac{2}{3}\right)\left(\frac{2}{3}+2\sqrt{x}\right)=\left(2\sqrt{x}-\frac{2}{3}\right)\left(2\sqrt{x}+\frac{2}{3}\right)\)
\(=\left(2\sqrt{x}\right)^2-\left(\frac{2}{3}\right)^2\)
Trả lời:
a, \(\left(\frac{x}{y}-\frac{2}{3}\right)\left(\frac{x}{y}+\frac{2}{3}\right)\)\(=\left(\frac{x}{y}\right)^2-\left(\frac{2}{3}\right)^2=\frac{x^2}{y^2}-\frac{4}{9}\)
b, \(\left(2\sqrt{x}-\frac{2}{3}\right)\left(\frac{2}{3}+2\sqrt{x}\right)=\left(2\sqrt{x}-\frac{2}{3}\right)\left(2\sqrt{x}+\frac{2}{3}\right)=\left(2\sqrt{x}\right)^2-\left(\frac{2}{3}\right)^2=4x-\frac{4}{9}\)
\(4x^4-4x^2+1=\left(2x^2-1\right)^2\)
\(\left(x+2y\right)^2=x^2+4xy+4y^2\)
\(36-12x+x^2=\left(6-x\right)^2\)
\(\left(x+5y\right)^2=x^2+10xy+25y^2\)
\(4x^2-12x+9=\left(2x-3\right)^2\)
\(\left(x-2y\right)^2=x^2-4xy+4y^2\)
Trả lời:
a, \(\left(3\sqrt{x}-y\right)\left(3\sqrt{x}+y\right)=\left(3\sqrt{x}\right)^2-y^2=9x-y^2\)
b, \(\left(\sqrt{x}-2\sqrt{y}\right)\left(2\sqrt{y}+\sqrt{x}\right)=\left(\sqrt{x}-2\sqrt{y}\right)\left(\sqrt{x}+2\sqrt{y}\right)=\left(\sqrt{x}\right)^2-\left(2\sqrt{y}\right)^2\)
\(=x-4y\)
Ta có :
\(\left(3x^2+2y\right)\left(2y-3x^2\right)\)
\(=\left(2y+3x^2\right)\left(2y-3x^2\right)\)
\(=\left(2y\right)^2-\left(3x^2\right)^2\)
\(=4y^2-9x^4\)
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/ \(\left(\sqrt{x}-2\sqrt{y}\right)^2=\left(\sqrt{x}\right)^2-2\sqrt{x}.2\sqrt{y}+\left(2\sqrt{y}\right)^2=x-4\sqrt{xy}+4y\)