Question

The second term of arithematic proggresions 7. and the sum of the first four termd is 12 find

Answer 1

Answer:

a) a1=15 first term

b) d=-8 common difference

Step-by-step explanation:

1)a1+d=7

2)a1+a2+a3+a4=12

a1+a1+d+a1+2d+a1+3d=12

4a1+6d=12

2a1+3d=6

We have the system of equations where a1+d=7 and 2a1+3d=6

3a1+3d=21

2a1+3d=6

Subtract the second equation from the first one

a1=15

d=-8