Question

Sum of first three tetms in an Ap is 15, and sum of next three terms is 42 find the sum of 10 terms

Answer 1

Answer:

126

Step-by-step explanation:

Step-by-step explanation:

first three terms sum = 15

that is a+a+d+a+2d =15

3a + 3d = 15

a+d = 15------------@

also next 3 terms sum =42

that is a+3d+a+4d+a+5d = 42

3a+12d= 42

a+4d= 14------------@

subtracting both the equation

a=2 and d=3

so sum of nine terms Sn = n/2[2a + (n-1)d

put n=9

so Sn = 126

HOPE IT HELPS!!

Answer 2

Answer:

155

Ap series is

2,5,8..10th term

Sum =n/2 (2a+(n-1)d)

10/2(2.2+(10-1).3)

=155

Step-by-step explanation: