Question

10) Find five terms in A.P. whose sum is 60 and the product of
last two terms is 320.

Answer 1

Answer:

4,8,12,16,20

Step-by-step explanation:

A.P terms for five consecutive

a-2d,a-d,a,a+d,a+2d

now sum of all terms =60

then, 5a=60

a=12.

now products of last two terms

(a+d)×(a+2d)=320

a2+2ad+ad+2d2=320

now put a=12

144+36d+12d+2d2=320

d2+22d-4d-88=0

d(d-4)+22(d-4)=0

d=4 and d=-22 which is not possible

therefore d=4 and a=12