The first three terms of an arithematic profgression are x,2x+y and 9x-y.The sum of these three terms is 60.Find the numerical values of x and y.Then,calculate the eleventh term of the progression

Answer 1

if in an AP,
2x+y - x = 9x-y - (2x+y)
x + y = 7x - 2y
3y = 6x
y = 2x

also: x + 2x+y + 9x - y = 60
12x = 60
x = 5 , then
y = 10
so the first term is x or 5
common difference = 2x+y - x
= x+y
= 15

term11 = a+10d = 5 +150 = 155

check:
first 3 terms are:
5 , 20 , 35, ...
is their sum = 60 ? YES

Answer 2

Yup..Thanks a lot!