Prove by mathematical induction that 1^2 + 2^2 ++k^2= k(k+1)(2k+1)/6

As usual, we start by checking that the base case holds: if we have

which is true. Now, we assume that

and we check : if we add the k+1-th term on both sides, we have

And our goal is to rearrange the right hand term as follows:

And we're done, because is exactly the formula if you substitute k with k+1

hi,

3. 12.15, you are correct.

4.2.01, your first digit is correct,

hope this !

19.side- angle- side

20. angle- side- angle

step-by-step explanation: