Proving GP Sum and Expanding Binomial Formula: 2n, 2x - 3y

[r-soy]

3 – If r = -1 and frist term is 1/2 find the sum of the 10 terms of a Gp

4 - Use mathematical induction to prove that 2 + 4 + 6 ……..+ 2n = n(n+1)

5 – Expand ( 2x – 3y)^4 by using binomial formula

Notice :
D. Mark i can't type my work into the text entry box. i put it in attachment I'm very sorry

 

[Mark44]

3. S₁₀ isn't 1/11. a₁ = ? r = ? n = ? Substitute these values into your formula.
4. That's not how you do a proof by induction.
Show that the statement is true for some base case such as n = 1. (What does the formula look like if n = 1? Is it true for that case?)
Assume that the statement is true for n = k. (What does the formula look like for that case?)
Use your assumption in the previous step to show that the statement is true for n = k + 1.

5. You're sort of on the right track here, but you mixed up 2x by using 3x.