surface area (S) of a right rectangular solid is:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
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you have:
L = 7
W = a
H = 4
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formula becomes:
S = 2*7*a + 2*7*4 + 2*a*4
simplify:
S = 14*a + 56 + 8*a
combine like terms:
S = 22*a + 56
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answer is:
S = 22*a + 56 (equation 2)
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to prove, substitute any value for a in equation 2:
let a = 15
S = 22*a + 56 (equation 2)
S = 22*15 + 56
S = 330 + 56
S = 386
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since a = 15, then W = 15 because W = a
go back to equation 1 and substitute 15 for W:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
-----
you have:
L = 7
W = 15
H = 4
-----
equation 1 becomes:
S = 2*7*15 + 2*7*4 + 2*15*4
perform indicated operations:
S = 210 + 56 + 120
S = 386
-----
surface area is the same using both equations so:
equations are good.
formula for surface area of right rectangle in terms of a is:
S = 22*a + 56
-----
Answer:
y=25
Step-by-step explanation:
y=4+4x+x^2
x=3
y=4+4(3)+(3)^2
y=4+12+(3)^2
y=4+12+(3x3)
y=4+12+(9)
y=16+9
y=25
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<span>
it consists of a rectangle, dimensions L = 4ft and W = 3ft = Ar = 4ft x 3ft = 12 ft^2
</span>then, you have one half of the area of the circle that has diameter R = 3ft - radius will be r = 1.5ft the area of that half will be:
Ac = r^2

/ 2
= (1.5 ft)^2 x 3.14 / 2
= 2.25 ft^2 x 3.4/2
= 7.065 ft^2/ 2
= 3.5325ft^2
A = Ar + Ac
A = 12ft^2 + 3.5325ft^2
A = 15.5325ft^2
<span>At the rate of $2 per square foot, the cost will be:
$ 15.5325*2 = 31.07 </span>
3 times 7.75 = 23.25 + 7.75 = 31.00
so the basketball is $23.25 and the pump is $7.75