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The surface area of a cylinder is 972xPi and the diameter of the top circle is 2x and the length is 5x..... solve for x.....tf how do you do this question..

-the answer is 9 i just don't know how to do the question 

 Jun 3, 2021
 #1
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Surface  area of  a cylinder  =   2pi  r^2    +   2pi  r  h

 

If  the diameter = 2x......then the  radius =  x

 

So  we  have  this

 

972 pi  =   2pi  *x^2  +  2pi * x  * 5x        divide out pi  and simplify

 

972  =  2x^2   + 10x^2          divide through  by 2

 

486  = x^2  + 5x^2

 

486  =  6x^2      divide both sides by 6

 

81  =  x^2         take the positive root of both sides

 

9  =  x

 

 

 

cool cool cool

 Jun 3, 2021
edited by CPhill  Jun 3, 2021

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