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How does 3^(k+1)-3+2×3^(k+1) simplify to 3(3^(k+1)-1)?
Original post by Risermax
Please Help!

How does 3^(k+1)-3+2×3^(k+1) simplify to 3(3^(k+1)-1)?


Your first line of working should be to add 3^(k + 1) and 2x3^(k + 1) together.

Post your working if stuck.
Reply 2
Original post by old_engineer
Your first line of working should be to add 3^(k + 1) and 2x3^(k + 1) together.

Post your working if stuck.

How do you do 3^(k+1)+6^(k+1)?
Original post by Risermax
How do you do 3^(k+1)+6^(k+1)?

I took 2x3^(k + 1) to mean 2 x (3^(k+1)). Is it actually (2 x 3)^(k + 1)? What is the exact notation used in the question?
Reply 4
Original post by old_engineer
I took 2x3^(k + 1) to mean 2 x (3^(k+1)). Is it actually (2 x 3)^(k + 1)? What is the exact notation used in the question?

Oh no I was wrong you're right but still how would you add 3^(k+1) to 2×(3^(k+1))
Reply 5
Original post by Risermax
Oh no I was wrong you're right but still how would you add 3^(k+1) to 2×(3^(k+1))

the same way you add an orange to two oranges, or x to 2x :smile: You're overthinking things here! You have "something" and another 2 lots of the "something" to add to it :smile:
Original post by Risermax
Oh no I was wrong you're right but still how would you add 3^(k+1) to 2×(3^(k+1))

Just to paraphrase what @davros said, if you let A = 3^(k + 1) then the addition you need to do can be stated as A + 2A.

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