Question

Proof by mathematical induction

Answer 1

Answer:

See below.

Step-by-step explanation:

I will assume that 3n is the last term.

First let  n = k, then:

Sum ( k terms) =  7k^2 + 3k

Now, the sum of k+1 terms  = 7k^2 + 3k + (k+1) th term

=  7k^2 + 3k + 14(k + 1) - 4

=   7k^2 + 17k + 10

Now 7(k + 1)^2 = 7k^2 +14 k + 7 so

7k^2 + 17k + 10

=  7(k + 1)^2  + 3k  + 3

= 7(k + 1)^2 + 3(k + 1)

Which is the  formula for the Sum of k terms with the k replaced by k + 1.

Therefore we can say if the sum formula is true for k terms then it is also true for (k + 1) terms.

But the formula is true for 1 term because  7(1)^2 + 3(1) = 10 .

So it must also be true for all subsequent( 2,3 etc) terms.

This completes the proof.