Question

khai triển các hằng đẳng thức sau:

a. \(\left(2xy-3\right)^2\)

b. \(\left(\dfrac{1}{2}x+\dfrac{1}{3}\right)^2\)

Answer 1

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

\(b.\left(\dfrac{1}{2}x+\dfrac{1}{3}\right)^2=\dfrac{1}{4}x^2+\dfrac{1}{3}x+\dfrac{1}{9}\)

Answer 2

a) (2xy)²-2(2xy-3)+3²

Answer 3

a)\(\left(2xy-3\right)^2=\left(2xy\right)^2-2\cdot2xy\cdot3+3^2=4x^2y^2-12xy+9\)

b)\(\left(\dfrac{1}{2}x+\dfrac{1}{3}y\right)^2=\left(\dfrac{1}{2}x\right)^2+2\cdot\dfrac{1}{2}x\cdot\dfrac{1}{3}y+\left(\dfrac{1}{3}y\right)^2\)

                          \(=\dfrac{1}{4}x^2+\dfrac{1}{3}xy+\dfrac{1}{9}y^2\)

Answer 4

b: \(=\dfrac{1}{4}x^2+\dfrac{1}{3}x+\dfrac{1}{9}\)

Answer 5

(2xy - 3)² = (2xy)² - 2 x 2xy x 3 +3²

= 4x²y² - 12xy +9