Question

Bài 1: Viết các biểu thức sau dưới dạng tổng:

a) (5x + 2y)²

b) (-3x + 2)²

c) (\(\dfrac{2}{3}\)x + \(\dfrac{1}{3}\)y)²

d) (2x - \(\dfrac{5}{2}\)y)²

e) (x + \(\dfrac{4}{3}\)y²)²

f) (2x² + \(\dfrac{5}{3}\)y)²

Answer 1

a ) \(\left(5x+2y\right)^2=25x^2+20xy+4y^2\)

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

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

d ) \(\left(2x-\dfrac{5}{2}y\right)^2=4x^2-10xy+\dfrac{25}{4}y^2\)

e ) \(\left(x+\dfrac{4}{3}y^2\right)^2=x^2+\dfrac{8}{3}xy^2+\dfrac{16}{9}y^4\)

f ) \(\left(2x^2+\dfrac{5}{3}y\right)^2=4x^4+\dfrac{20}{3}x^2y+\dfrac{25}{9}y^2\)