Ans is 90/(v-3)-90/(v+3) to solve to get answer
but it requires finding square root of 1071 I think. How am I supposed to fig out square in such a time of such a number.
Thanks
Khurram
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gmatinjuly
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I think you did a calculation mistake somewhere
90/v-3 - 90/ v+3 = 1/2
90 [ 1/v-3 - 1/v+3 ] = 1/2
1/v-3 - 1/v+3 = 1/180
v+3-v+3 / v^2 -9 = 1/180
6/(v^2 -9) = 1/180
v^2 - 9 = 180*6
v^2-9 = 1080
v^2 = 1089 (you subtracted 9 hence u got 1071)
1089 = 121 * 9
v = 11 * 3 = 33
time = 90/36 = 15 / 6 = 5 /2 = 2.5 hours
90/v-3 - 90/ v+3 = 1/2
90 [ 1/v-3 - 1/v+3 ] = 1/2
1/v-3 - 1/v+3 = 1/180
v+3-v+3 / v^2 -9 = 1/180
6/(v^2 -9) = 1/180
v^2 - 9 = 180*6
v^2-9 = 1080
v^2 = 1089 (you subtracted 9 hence u got 1071)
1089 = 121 * 9
v = 11 * 3 = 33
time = 90/36 = 15 / 6 = 5 /2 = 2.5 hours
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mim3
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Why not just plug in the answers and see if it computes? I did it that way and got it very quickly (I started with a). Even if you started with e and went backwards, it's at most a 2 minute problem.
