SOLUTION: If {{{k=((x+1)(x-1))/3}}} and k=0, what does {{{3x^2}}} equal in terms of k? A) 3k B) 9k C) 3k+1 D) 9k+3

Algebra ->  Expressions -> SOLUTION: If {{{k=((x+1)(x-1))/3}}} and k=0, what does {{{3x^2}}} equal in terms of k? A) 3k B) 9k C) 3k+1 D) 9k+3      Log On


   

Question 1043620: If k=%28%28x%2B1%29%28x-1%29%29%2F3 and k=0, what does 3x%5E2 equal in terms of k?
A) 3k
B) 9k
C) 3k+1
D) 9k+3
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!



First solve for x^2


k+=+%28%28x%2B1%29%28x-1%29%29%2F3


3k+=+3%2A%28%28%28x%2B1%29%28x-1%29%29%2F3%29 Multiply both sides by 3


3k+=+%28x%2B1%29%28x-1%29


3k+=+x%5E2-1 Use the difference of squares rule


3k%2B1+=+x%5E2-1%2B1 Add 1 to both sides


3k%2B1+=+x%5E2


x%5E2+=+3k%2B1


Now multiply both sides by 3


x%5E2+=+3k%2B1


3x%5E2+=+3%283k%2B1%29


3x%5E2+=+9k%2B3


The final answer is choice D) 9k+3