(r-3)(r+11)=-4

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Solution for (r-3)(r+11)=-4 equation:


Simplifying
(r + -3)(r + 11) = -4

Reorder the terms:
(-3 + r)(r + 11) = -4

Reorder the terms:
(-3 + r)(11 + r) = -4

Multiply (-3 + r) * (11 + r)
(-3(11 + r) + r(11 + r)) = -4
((11 * -3 + r * -3) + r(11 + r)) = -4
((-33 + -3r) + r(11 + r)) = -4
(-33 + -3r + (11 * r + r * r)) = -4
(-33 + -3r + (11r + r2)) = -4

Combine like terms: -3r + 11r = 8r
(-33 + 8r + r2) = -4

Solving
-33 + 8r + r2 = -4

Solving for variable 'r'.

Reorder the terms:
-33 + 4 + 8r + r2 = -4 + 4

Combine like terms: -33 + 4 = -29
-29 + 8r + r2 = -4 + 4

Combine like terms: -4 + 4 = 0
-29 + 8r + r2 = 0

Begin completing the square.

Move the constant term to the right:

Add '29' to each side of the equation.
-29 + 8r + 29 + r2 = 0 + 29

Reorder the terms:
-29 + 29 + 8r + r2 = 0 + 29

Combine like terms: -29 + 29 = 0
0 + 8r + r2 = 0 + 29
8r + r2 = 0 + 29

Combine like terms: 0 + 29 = 29
8r + r2 = 29

The r term is 8r.  Take half its coefficient (4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
8r + 16 + r2 = 29 + 16

Reorder the terms:
16 + 8r + r2 = 29 + 16

Combine like terms: 29 + 16 = 45
16 + 8r + r2 = 45

Factor a perfect square on the left side:
(r + 4)(r + 4) = 45

Calculate the square root of the right side: 6.708203933

Break this problem into two subproblems by setting 
(r + 4) equal to 6.708203933 and -6.708203933.

Subproblem 1

r + 4 = 6.708203933 Simplifying r + 4 = 6.708203933 Reorder the terms: 4 + r = 6.708203933 Solving 4 + r = 6.708203933 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + r = 6.708203933 + -4 Combine like terms: 4 + -4 = 0 0 + r = 6.708203933 + -4 r = 6.708203933 + -4 Combine like terms: 6.708203933 + -4 = 2.708203933 r = 2.708203933 Simplifying r = 2.708203933

Subproblem 2

r + 4 = -6.708203933 Simplifying r + 4 = -6.708203933 Reorder the terms: 4 + r = -6.708203933 Solving 4 + r = -6.708203933 Solving for variable 'r'. Move all terms containing r to the left, all other terms to the right. Add '-4' to each side of the equation. 4 + -4 + r = -6.708203933 + -4 Combine like terms: 4 + -4 = 0 0 + r = -6.708203933 + -4 r = -6.708203933 + -4 Combine like terms: -6.708203933 + -4 = -10.708203933 r = -10.708203933 Simplifying r = -10.708203933

Solution

The solution to the problem is based on the solutions from the subproblems. r = {2.708203933, -10.708203933}

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