Question

in an AP if a2 =13,a4 =3 find a and a3?

Answer 1

a+d=13
a+3d=3
By solving the equations
-2d=10
d=-10/2
d=-5
Substituting d=-5 in a+3d=3
a=3-3d
a=3-3(-5)
a=3+15
a=18
a 3=a+2d=18+2(-5)
a 3=18-10
a 3=8

Answer 2

A2=a+d=13 .....(1)
A4=a+3d=3.....(2)
Solve equipment(1)and(2)
A+3d=3
A+d=13
2d=-10
D=-5
Substituting d=-5in equipment(1)
A+(-5)=13
A=13+5=18
A3=a+2d=18+(-5)=18-10=8