Question 998847


{{{(2x + 5)^2 - (x - 4)^2}}}....recall:{{{a^2 - b^2=(a-b)(a+b)}}}

in your case {{{a=(2x + 5)}}} and {{{b=(x - 4)}}}; so, you have

{{{((2x + 5) - (x - 4))((2x + 5) +(x - 4))}}}

{{{(2x + 5 - x +4)(2x + 5 +x - 4)}}}

{{{(x + 9)(3x + 1)}}}