Question

10. 3(x2+2x) = 27

Answer 1

\[3(x^2+2x)=27\]
\[x^2+2x=9\]
\[(x+1)^2=9+1=10\]
\[x+1=\pm\sqrt{10}\]
\[x=-1\pm\sqrt{10}\]

Answer 2

or if you don't like completing the square you can write
\[x^2+2x-9=0\] and use the quadratic formula

Answer 3

what would you call that symbol that looks like a plus sign with an extra line running through it? The one you listed in the last part of the equation.

Answer 4

That's a plus or minus sign. It just means that the number that follows that sign could either be a positive integer or a negative integer.