solve

[soprano]

5a+b=4
b=40-a^2

This is what I have done so far:
5a+40-a^2=4
a(5-a)=-36

I totally don't know what I am doing.

 

[galactus]

Sub b into the first equation.

This gives:

\(\displaystyle 5a+40-a^{2}=4\)

Rearrange to make a nice quadratic:


\(\displaystyle a^{2}-5a-36=0\)

Now factor away.

 

[soprano]

so a=-4 or a=9 correct?
would the answer be written (-4,9)

 

[galactus]

Just write it as a=9 or a=-4.

Written the other way makes it look like corrdinates.