Question

Khai triển

a) \(\left(2x-5y\right)^2\)

b) \(\left(3x+2y\right)^2\)

c) \(\left(3x+4y\right)\left(4y-3x\right)\)

 

 

Answer 1

Lời giải:

a. $=(2x)^2-2.2x.5y+(5y)^2=4x^2-20xy+25y^2$
b. $=(3x)^2+2.3x.2y+(2y)^2=9x^2+12xy+4y^2$

c. $=(4y+3x)(4y-3x)=(4y)^2-(3x)^2=16y^2-9x^2$

Answer 2

\(a.4x^2-10xy+25y^2\)

\(b.9x^2+6xy+4y^2\)

\(c.16y^2-9x^2\)