Tentukan nilai x, jika (2x+1) + (2x + 2) + (2x + 3) + ……. + (2x + 50) = 4275


(2x+1)+(2x+2)+(2x+3)+……+(2x+50) = 4275, 50(2x) + 1+50 . 25 =4275, 100x + 1275 = 4275, x = 4275 – 1275 / 100, x = 3000 / 100, x = 30
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A=U1=2x+1, U2=2x+2, b=U2-U1=2x+2-(2x+1)=1, Un=a+(n-1)b, =2x+1+(n-1)1=2x+50, 2x+n=2x+50, n=50, Sn=n/2(a+Un), =50/2(2x+1+(2x+50))=4275, =25(4x+51)=4275, =100x+1275=4275, =100x=3000, x=30,