Question

how many terms of AP 16, 14,12 are needed to give the sum 60? explain why we get two answers​

Answer 1

Answer:

Step-by-step explanation:

We know that Sn = n/2(2a+(n-1)d)

60 = n/2(2*16+(n-1)(-2))

120 = n(34 - 2n)

120 = 34n-2n^2

n^2 -17n+60=0

n^2 -12n-5n+60=0

n=5 or 12.

Here, we get 2 answers because of a quadratic equation giving both +ve values.