difference between the squares of 2 consecutive multiples

[Cortezz]

i need help with this problem. It says (the difference between the squares of two consecutive multiples of three is 1989. Show how you found the solution.)


HOW DO I DO THIS!!!!!!

 

[Denis]

Re: difference between the squares of 2 consecutive multiple

i need help with this problem. It says (the difference between the squares of two consecutive multiples of three is 1989. Show how you found the solution.)

k = any integer
3k = lower multiple, 3(k+1) = next multiple

(3(k+1))^2 - (3k)^2 = 1989
9k^2 + 18k + 9 - 9k^3 = 1989

Finish it; if you can't, you're not ready for a problem like this one.