72=x(x-1)/2

Solution for 72=x(x-1)/2 equation:

72=x(x-1)/2

We move all terms to the left:

72-(x(x-1)/2)=0

We multiply all the terms by the denominator


-(x(x-1)+72*2)=0


We calculate terms in parentheses: -(x(x-1)+72*2), so:

x(x-1)+72*2

We add all the numbers together, and all the variables

x(x-1)+144

We multiply parentheses

x^2-1x+144

Back to the equation:

-(x^2-1x+144)


We get rid of parentheses

-x^2+1x-144=0

We add all the numbers together, and all the variables

-1x^2+x-144=0

a = -1; b = 1; c = -144;
Δ = b2-4ac
Δ = 12-4·(-1)·(-144)
Δ = -575
Delta is less than zero, so there is no solution for the equation