Question

find the first term and difference of an ap if the sum of first five even terms is 15 and the sum of the first three terms is equal to -3
guys please answer this question,1 will mark you as brainlist​

Answer 1

Answer:

1st term=-5, difference=4

Step-by-step explanation:

Sum of 1  

st

 seven terms

15=  

2

5

​  

(2a+(5−1)d)

3=a+  

2

4d

​  

 

3=a+2d−(i)

Sum of 1  

st

 3 terms=3

So,3a+3d=−3 [Considering 1  

st

 term as a,a+d,a+2d]

a+d=−1−(ii)

Solving (i) & (ii)

d=3−(−1)

d=4

Putting value of d in (ii)

a+4=−1

a=−5

So first term=−5 and difference =4