Question 1022705
<pre>
Solve a+2b = 9 for a, get a = 9-2b

Square both sides of 

a+2b = 9

Substitute ab=7 for ab, and (9-2b) for a

Simplify, get 0 on the right side.

You get a quadratic equation in b that you 
can divide thru by 4.

Simplify

The quadratic equation is factorable

You get 2 solutions for b

Substitute each in a = 9-2b to find two solutions for a

Substitute the values of a and b in

aČ+4b, and get 2 solutions.

Edwin</pre>