Diketahui suatu bsrisan aritmatika U2+U7=26 dan U5+U3=22 .tentukan besarnya suko ke-10?

U2 + U7 = 26
a + b + a + 6b = 26
2a + 7b = 26

U5 + U3 = 22
a + 4b + a + 2b = 22
2a + 6b = 22

2a + 7b = 26
2a + 6b = 22
------------------- (-)
b = 4

2a + 6b = 22
a + 3b = 11
a + 12 = 11
a = -1

U10 = a + 9b
U10 = -1 + 9(4)
U10 = -1 + 36
U10 = 35

u2+u7=26
a+(n-1)b=Un
a+(2-1)b=U2
a+b=U2
a+(7-1)b=U7
a+6b=U7
u2+u7=26
a+b + a+6b = 26
2a+7b=26

u5+u3=22
a+(n-1)b=Un
a+(5-1)b=U5
a+4b=U5
a+(3-1)b=U3
a+2b=U3
U5+U3=22
a+4b + a+2b = 22
2a+6b = 22

dieliminasi
2a+7b= 26
2a+6b= 22  -
hasil : b=4
          a=-1

U10 = a + (n-1)b
= (-1) + (10-1)4
= (-1) + 9x4
= (-1) + 36
= 35