Respuesta :

choixongdong
using(a+b)^2 = a^2 + 2ab = b^2

so

(3x + 7y)^2
= 9x^2 + 42xy + 49y^2

answer
9x^2 + 42xy + 49y^2
calculista

Answer:

[tex]9x^{2}+42xy+49y^{2}[/tex]

Step-by-step explanation:

we know that

[tex](a+b)^{2}=a^{2}+2ab+b^{2}[/tex]

In this problem we have

[tex](3x+7y)^{2}[/tex]

so

[tex]a=3x[/tex]

[tex]b=7y[/tex]

substitute

[tex](3x+7y)^{2}=(3x)^{2}+2(3x)(7y)+(7y)^{2}[/tex]

[tex]=9x^{2}+42xy+49y^{2}[/tex]