Prove by Mathematical Induction that for .

Step 1: Prove true for n = 1

hence true for n = 1

Step 2: Assume true for n = k

Step 3: Prove true for n = k + 1

LHS =

not really sure what to do from here, tried this approach

since from step 2 we know that , but not sure if this is right as I do not know what to do with the 2k - 10

any insight appreciated