Answer:
The equation for nth term is 3n + 5.
Step-by-step explanation:
Let a1 be a,
a3 = a + (n - 1)d
or, 14 = a + (3 - 1)d
so, 14 = a + 2d
Now,
a5 = a + (n - 1)d
or, 20 = a + (5 - 1)d
or, 20 = a + 4d
now,
a + 4d = 20
a + 2d = 14
now,
a + 4d - ( a + 2d) = 20 - 14
or, a + 4d - a - 2d = 6
or, 2d = 6
so, d = 3
Now,
a + 2d = 14
or, a + 2(3) = 14
or, a = 14 - 6
so, a = 8
Now,
an = a + (n - 1)d
or, an = 8 + (n - 1)3
or, an = 8 + 3n - 3
so, an = 3n + 5
