Question

Bailey writes the expression g2 + 14g + 40 to represent the area of a planned school garden in square feet. If g = 5, what are the dimensions of the school garden?

20 feet by 2 feet
10 feet by 4 feet
12 feet by 7 feet
15 feet by 9 feet

Answer 1

The expression is $A=g^2 + 14g + 40$.
$D=14^2-4\cdot 40=196-160=36 \\ \sqrt{D}=6 \\ q_{1,2}= \dfrac{-14\pm 6}{2} =-4,-10$.
Then $A=g^2 + 14g + 40=(g+4)(g+10)$.
The width is g+4, the length is g+10.
When g=5, 
g+4=9 ft and g+10=15 ft.
Answer: correct choice is D.