126=n(n-1)/2

Solution for 126=n(n-1)/2 equation:

126=n(n-1)/2

We move all terms to the left:

126-(n(n-1)/2)=0

We multiply all the terms by the denominator


-(n(n-1)+126*2)=0


We calculate terms in parentheses: -(n(n-1)+126*2), so:

n(n-1)+126*2

We add all the numbers together, and all the variables

n(n-1)+252

We multiply parentheses

n^2-1n+252

Back to the equation:

-(n^2-1n+252)


We get rid of parentheses

-n^2+1n-252=0

We add all the numbers together, and all the variables

-1n^2+n-252=0

a = -1; b = 1; c = -252;
Δ = b2-4ac
Δ = 12-4·(-1)·(-252)
Δ = -1007
Delta is less than zero, so there is no solution for the equation