SAT question, level of difficulty: HARD -
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The surface area, S, of a cylinder with a radius of 5 is defined by , where h is the height of the cylinder. If the equation is rewritten in the form , where x and y are constants, what is the value of y ? (Surface Area )
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The answer is y = 5, but I can't figure out how, please help.

y = 5

Explanation:

S = 2π r² + 2π r h

let r = 5

let h = height of the cylinder

since the equation is re-written in the form h =

where x and y are constants.

what is the value of y?

S = (2π r²) + (2π r h)  ------ plug in r = 5

S = (2π * 5²) + (2π * 5 * h)

S = (2π * 50) + (10π h)

S = 50π + 10π h

S - 50π = 10π h

     S - 50π

h = -------------

         10π

       S         50π

h = ------  -  ---------

     10π         10π

       S        

h = ------  -  5

     10π      

therefore,  the value of y = 5

remember the re-written equation  h =

and x and y are constants.

x = 10π as constant

y = 5 as constant

hope it clears your mind.

answer:

is this serious

explanation: