Changes

2ab = <math>b^{2}</math> + bc ---------->1<br>

2ab = <math>b^{2}</math> + bc ---------->1<br>

Also 'b' is the geometric mean between 'a' and 'c'<br>

Also 'b' is the geometric mean between 'a' and 'c'<br>

That is b = <math>\sqrt{ac}</math> ------------------> 2<br>

That is b = <math>\sqrt{ac}</math><br>

We also write this as b^{2} = ac.<br>

Now substitute

Now substitute