Question 575668
{{{(x+4)(x+14)=900}}}
how did i get this equation?

the frame is 2 inches thick so theres 2 inches on left side of the length and 2 inches on the right side so thats 4 more inches than the lenth of the picture
same goes for the width 2 in on top 2 inches on bottom makes 4 more inches added to width
{{{LW=A}}} length times width equals area
{{{A=900}}}
{{{L=x+4}}}
{{{W=(x+10)+4}}}
{{{W=x+14}}}
back to the equation
{{{(x+4)(x+14)=900}}} FOIL (First Outer Inner Last)
F {{{x*x=x^2}}}
O {{{x*14=14x}}}
I {{{4*x=4x}}}
L {{{4*14=56}}}
{{{x^2+14x+4x+56=900}}} add like terms
{{{x^2+18x+56=900}}}subtract 900 from both sides
{{{x^2+18x-844=0}}} use quadratic formula to solve
*[invoke quadratic "x", 1, 18, -844]