k^2=-4k+21

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Solution for k^2=-4k+21 equation:


Simplifying
k2 = -4k + 21

Reorder the terms:
k2 = 21 + -4k

Solving
k2 = 21 + -4k

Solving for variable 'k'.

Reorder the terms:
-21 + 4k + k2 = 21 + -4k + -21 + 4k

Reorder the terms:
-21 + 4k + k2 = 21 + -21 + -4k + 4k

Combine like terms: 21 + -21 = 0
-21 + 4k + k2 = 0 + -4k + 4k
-21 + 4k + k2 = -4k + 4k

Combine like terms: -4k + 4k = 0
-21 + 4k + k2 = 0

Factor a trinomial.
(-7 + -1k)(3 + -1k) = 0

Subproblem 1

Set the factor '(-7 + -1k)' equal to zero and attempt to solve: Simplifying -7 + -1k = 0 Solving -7 + -1k = 0 Move all terms containing k to the left, all other terms to the right. Add '7' to each side of the equation. -7 + 7 + -1k = 0 + 7 Combine like terms: -7 + 7 = 0 0 + -1k = 0 + 7 -1k = 0 + 7 Combine like terms: 0 + 7 = 7 -1k = 7 Divide each side by '-1'. k = -7 Simplifying k = -7

Subproblem 2

Set the factor '(3 + -1k)' equal to zero and attempt to solve: Simplifying 3 + -1k = 0 Solving 3 + -1k = 0 Move all terms containing k to the left, all other terms to the right. Add '-3' to each side of the equation. 3 + -3 + -1k = 0 + -3 Combine like terms: 3 + -3 = 0 0 + -1k = 0 + -3 -1k = 0 + -3 Combine like terms: 0 + -3 = -3 -1k = -3 Divide each side by '-1'. k = 3 Simplifying k = 3

Solution

k = {-7, 3}

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