x^2-42x-7=0

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Solution for x^2-42x-7=0 equation:


Simplifying
x2 + -42x + -7 = 0

Reorder the terms:
-7 + -42x + x2 = 0

Solving
-7 + -42x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '7' to each side of the equation.
-7 + -42x + 7 + x2 = 0 + 7

Reorder the terms:
-7 + 7 + -42x + x2 = 0 + 7

Combine like terms: -7 + 7 = 0
0 + -42x + x2 = 0 + 7
-42x + x2 = 0 + 7

Combine like terms: 0 + 7 = 7
-42x + x2 = 7

The x term is -42x.  Take half its coefficient (-21).
Square it (441) and add it to both sides.

Add '441' to each side of the equation.
-42x + 441 + x2 = 7 + 441

Reorder the terms:
441 + -42x + x2 = 7 + 441

Combine like terms: 7 + 441 = 448
441 + -42x + x2 = 448

Factor a perfect square on the left side:
(x + -21)(x + -21) = 448

Calculate the square root of the right side: 21.166010489

Break this problem into two subproblems by setting 
(x + -21) equal to 21.166010489 and -21.166010489.

Subproblem 1

x + -21 = 21.166010489 Simplifying x + -21 = 21.166010489 Reorder the terms: -21 + x = 21.166010489 Solving -21 + x = 21.166010489 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '21' to each side of the equation. -21 + 21 + x = 21.166010489 + 21 Combine like terms: -21 + 21 = 0 0 + x = 21.166010489 + 21 x = 21.166010489 + 21 Combine like terms: 21.166010489 + 21 = 42.166010489 x = 42.166010489 Simplifying x = 42.166010489

Subproblem 2

x + -21 = -21.166010489 Simplifying x + -21 = -21.166010489 Reorder the terms: -21 + x = -21.166010489 Solving -21 + x = -21.166010489 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '21' to each side of the equation. -21 + 21 + x = -21.166010489 + 21 Combine like terms: -21 + 21 = 0 0 + x = -21.166010489 + 21 x = -21.166010489 + 21 Combine like terms: -21.166010489 + 21 = -0.166010489 x = -0.166010489 Simplifying x = -0.166010489

Solution

The solution to the problem is based on the solutions from the subproblems. x = {42.166010489, -0.166010489}

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