Which of the following represents the area of a rectangle whose length is 5x − 3 and whose width is x + 7? 5x2 − 21 5x2 + 9x − 21 5x2 + 32x − 21 5x2 − 32x − 21
we know that
the area of the rectangle is equal to
\(A=L*W\)
where
L is the length side of the rectangle
W is the width side of the rectangle
In this problem we have
\(L=(5x-3)\ units\\W=(x+7)\ units\)
substitute the values in the formula above to find the area
\(A=(5x-3)*(x+7)\)
\(A=(5x-3)*(x+7)\\A=5x*x+5x*7-3x-3*7\\A=5x^{2}+35x-3x-21\\A=5x^{2}+32x-21\)
therefore
the answer is the option
5x2 + 32x − 21