Math Help, please!!?

Question

ok. can someone work this problem and tell me how you got the answer?

thank you!

Solve the equation for n.

n(n+1)

S = -----------

2

i dont know why it comes out like that, but the n(n+1) goes above the line, and the 2 goes under the line.

Answer 1

S = [n(n + 1)] / 2   ...multiply both sides by 2

2S = n(n + 1)   ...distribute the n on the right side

2S = n² + n

0 = n² + n - 2S

Use the quadratic formula with a = 1, b = 1 and c = -2S.

n = (-b ± √(b² - 4ac))/(2a)

n = (-1 ± √(1² - 4*1*(-2S)))/(2*1)

n = (-1 ± √(1 - 4(-2S)))/2

n = (-1 ± √(1 + 8S))/2

n = -½ ± √(1 + 8S)/2

So the answer is n = -½ + √(1 + 8S)/2 or n = -½ - √(1 + 8S)/2

Hope this helps you!

Answer 2

so wats the problem?