tolong kak terimakasih

(Ut)²=a.U3
(x-14)²=(x-50)(x-5)
x²-14x+196=x²-55x+250
x²-x²-28x+55x=250-196
27x=54
x=2
(2-50),(2-14),(2-5)
-48,-12,-3
r=1/4
S∞ = a/1-r
=-48/1-1/4
=-48/3/4 = -64