Question

Find four numbers in A.P whose sum is 28 and the sum of whose squares is 216.

Answer 1

a-2d,a-d,a+d,a+2d..... ap
sum
a-2d+a-d+a+d+a+2d=28
4a=28
a=7
sum of sq.
(a-2d)^2 + (a-d)^2 + (a+d)^2 + ( a+2d)^2=216
4a sq. + 10d sq. = 216
4(7)^2 + 10d sq. = 216
196+10d sq. = 216
10d sq.=20
d sq. = 2
d= √2

7-2✓2,7-✓2,7+✓2,7+2✓2

Answer 2

Hope it helps you ...