Answers

2014-10-03T09:10:29+08:00
12rs² / √s - 60 ; r = -4 ; s = 9equal -1356

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2014-10-04T00:40:23+08:00
(12rs²/√s) - 60              r = -4;    s = 9
so
(12 . -4 . 81)/3  - 60        /  just plug in the values
=  - 1296 - 60  =  - 1356
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