Question 73456
Simplify by combining like terms.

the number x and the square root of 18, subtract 3 and the square root of 8x^2. 

Is this what you meant?
{{{x*sqrt(18)-3+sqrt(8x^2)}}}
{{{x*sqrt(9)*sqrt(2)-3+sqrt(4x^2)*sqrt(2)}}}
{{{x*3*sqrt(2)-3+2x*sqrt(2)}}}
{{{3x*sqrt(2)-3+2x*sqrt(2)}}}
{{{(3x+2x)*sqrt(2)-3}}}
{{{highlight(5x*sqrt(2)-3)}}}
This can also be written {{{5*sqrt(2)x-3}}}
or is this what you meant:
{{{x+sqrt(18)-3+sqrt(8x^2)}}}
{{{x+sqrt(9)*sqrt(2)-3+sqrt(4x^2)*sqrt(2)}}}
{{{highlight(x+3*sqrt(2)-3+2x*sqrt(2))}}}  This has no like terms.
Happy Calculating!!!!