Answer
$a^3+5a^2-5a+6$ centimeters
Work Step by Step
To find the area of this rectangle, , multiply the two sides. So the expression should be $(a+6)\times(a^2-a+1)$. Multiply each term by the other, remembering FOIL. You will get:
$aa^2+a(-a)+a*1+(6a^2+6(-a)+6*1)$
Then simplify and combine like terms.
$a^3+a(-a)+a*1+6a^2+6(-a)+6)$
Continue to simplify, paying attention to exponents and carefully observing negative sign rules.
$a^3-a^2+a+(6a^2-6a+6)$
Remove unnecessary parentheses and continue to combine terms.
$a^3-5a^2-5a+6$
