Question

. The area of the rectangle is 21x²+ 29x - 10.
Find the PERIMETER of the rectangle.

Answer 1

`\textit{area of a rectangle}\\\\ A=Lw ~~ \begin{cases} L=length\\ w=width\\[-0.5em] \hrulefill\\ A=21x^2 + 29x -10 \end{cases}\implies 21x^2 + 29x -10=Lw \\\\\\ (3x+5)(7x-2)=Lw\implies L=3x+5\hspace{5em}w=7x-2 \\\\[-0.35em] ~\dotfill\\\\ \stackrel{\textit{perimeter of a rectangle}}{2(L+w)}\implies 2[(3x+5)+(7x-2)] \\\\\\ 2[10x+3]\implies \boxed{20x+6}`