Jawabanmu

2014-05-13T17:08:12+07:00
2(p+l)=2x+20
2(p+8-x)=2x+20
2p+16-2x=2x+20
2p=4x+4
p=2x+2

(2x+2)(8-x)=16x-2x^2+16-2x=-2x^2+14x+16
turunan = -4x + 14=0
maka -4x=-14
x=3,5
p=2(3,5)+2 = 9
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