SOLUTION: when one edge of a cube decreased by 1cm, its volume is decreased by 91cm. find the length of a side of the orignal cube.
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Question 165553: when one edge of a cube decreased by 1cm, its volume is decreased by 91cm. find the length of a side of the orignal cube.
Found 2 solutions by scott8148, ankor@dixie-net.com:
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
(e-1)^3=e^3-91 __ (e-1)(e^2-2e+1)=e^3-91 __ e^3-2e^2+e-e^2+2e-1=e^3-91
subtracting e^3-91 __ -3e^2+3e+90=0 __ dividing by -3 __ e^2-e-30=0
factoring __ (e+5)(e-6)=0
e+5=0 __ e=-5 __ negative value not realistic
e-6=0 __ e=6
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
when one edge of a cube decreased by 1 cm, its volume is decreased by 91cm.
find the length of a side of the original cube.
:
Let x = side of original cube
then
x^3 = volume of original cube
:
the volume when one edge of the cube is decrease by a cm = x^2(x-1)
:
Original - one edge decreased = 91 cu/cm
x^3 - x^2(x-1) = 91
:
x^3 - x^3 + x^2 = 91
:
x^2 = 91
:
x =
x = 9.54 cm
:
:
Check solution:
9.54^3 -(9.54^2 * 8.54)
868 - 777 = 91
:
Please let me know which your responses are correct. I think they mean just
one dimension is decreased by 1 cm, the other remain the same.
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