Answer:
[tex]\frac{9}{4}[/tex]
Step-by-step explanation:
Here we will first split the middle term in such way that it is a product of 2 and some factor. In this case 3 can be splitter as product of 2 and 3/2.
We then add the square of 3/2 on both sides. Let us see how:
[tex]x^2+3x=6\\x^2+2*\frac{3}{2}*x=6\\x^2+2*\frac{3}{2}*x+(\frac{3}{2})^2=6+(\frac{3}{2})^2\\(x+\frac{3}{2})^2=6+\frac{9}{4}\\(x+\frac{3}{2})^2=\frac{33}{4}[/tex]
