+0

# What is the coefficient of \$xy\$ in the expansion of \$(3x+(2y+1))^2\$?

0
363
2
+1766

What is the coefficient of \$xy\$ in the expansion of \$(3x+(2y+1))^2\$?

Mellie  May 9, 2015

#1
+80774
+15

\$\$\$(3x+(2y+1))^2\$\$

This term would be

C(2,1)*(3x)^1 *(2y + 1)^1  =

2(3x)(2y + 1) =

6x(2y + 1) =

12xy + 6x

So....the coefficient is 12

CPhill  May 9, 2015
Sort:

#1
+80774
+15

\$\$\$(3x+(2y+1))^2\$\$

This term would be

C(2,1)*(3x)^1 *(2y + 1)^1  =

2(3x)(2y + 1) =

6x(2y + 1) =

12xy + 6x

So....the coefficient is 12

CPhill  May 9, 2015
#2
+91404
+10

Thanks Chris,

This can be easily done by any good yr 9 student.

\$\$\\\boxed{(a+b)^2=a^2+2ab+b^2}\\\\
so\\\\
(3x+(2y+1))^2\\
=(3x)^2+2*3x*(2y+1)+(2y+1)^2\\
=etc\\\\
\$The only term with xy is going to be \$ \\
2*3x*2y=12xy\\
\$so the coefficient of xy is 12\$\$\$

Melody  May 10, 2015

### 2 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details