a(a+4)=21

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Solution for a(a+4)=21 equation:


Simplifying
a(a + 4) = 21

Reorder the terms:
a(4 + a) = 21
(4 * a + a * a) = 21
(4a + a2) = 21

Solving
4a + a2 = 21

Solving for variable 'a'.

Reorder the terms:
-21 + 4a + a2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + 4a + a2 = 0

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

Subproblem 1

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

Subproblem 2

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

Solution

a = {-7, 3}

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