-d^2+13d-42=0

Solution for -d^2+13d-42=0 equation:

Simplifying
-1d2 + 13d + -42 = 0

Reorder the terms:
-42 + 13d + -1d2 = 0

Solving
-42 + 13d + -1d2 = 0

Solving for variable 'd'.

Factor a trinomial.
(-7 + d)(6 + -1d) = 0

Subproblem 1
Set the factor '(-7 + d)' equal to zero and attempt to solve:

Simplifying
-7 + d = 0

Solving
-7 + d = 0

Move all terms containing d to the left, all other terms to the right.

Add '7' to each side of the equation.
-7 + 7 + d = 0 + 7

Combine like terms: -7 + 7 = 0
0 + d = 0 + 7
d = 0 + 7

Combine like terms: 0 + 7 = 7
d = 7

Simplifying
d = 7
Subproblem 2
Set the factor '(6 + -1d)' equal to zero and attempt to solve:

Simplifying
6 + -1d = 0

Solving
6 + -1d = 0

Move all terms containing d to the left, all other terms to the right.

Add '-6' to each side of the equation.
6 + -6 + -1d = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1d = 0 + -6
-1d = 0 + -6

Combine like terms: 0 + -6 = -6
-1d = -6

Divide each side by '-1'.
d = 6

Simplifying
d = 6
Solution
d = {7, 6}