An expression that could be used to multiply 6x198 mentally
2 answers:
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Answer:
Step-by-step explanation:
Start by setting the width = x.
Length is equal to x+20.
We know the cost of the land was $12 per square foot (area) and the cost of the fence around the perimeter is equal to $8 per foot. This gives us two equations we need to work with.
$12(x*(x+20)) + $8((2*x)+(2*(x+20))) = 10560. It looks a little difficult to read but as we distribute the cost throughout the equations, we see it start to take shape.
12(x^2+20x) + 8(2x+2x+40) = 10560
12x^2+240x+16x+16x+320 = 10560
12x^2+272x+320=10560
The roots of our equation here are x=20, and x = -128/3
Since we know that area is not negative, our answer is x=20.
Check the work: 12(20)^2 + 272(20) +320 = 10560