Question

How many term of A.P 16,14,12....are needed
to give the sum 60? Explain why we get a double
answer​

Answer 1

Step-by-step explanation:

n/2{2a+(n-1)d} =Sn

n/2{2×16 + (n-1) -2 = 60

n/2{32 +(n-1) -2 =60

16n + {-n²+n} = 60

16n-n²+n=60

n²-16n+60=0

n² - (10+6) n + 60 =0

(n-10)(n-6) =0