x^2-42x+840=0

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Solution for x^2-42x+840=0 equation:


Simplifying
x2 + -42x + 840 = 0

Reorder the terms:
840 + -42x + x2 = 0

Solving
840 + -42x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-840' to each side of the equation.
840 + -42x + -840 + x2 = 0 + -840

Reorder the terms:
840 + -840 + -42x + x2 = 0 + -840

Combine like terms: 840 + -840 = 0
0 + -42x + x2 = 0 + -840
-42x + x2 = 0 + -840

Combine like terms: 0 + -840 = -840
-42x + x2 = -840

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 = -840 + 441

Reorder the terms:
441 + -42x + x2 = -840 + 441

Combine like terms: -840 + 441 = -399
441 + -42x + x2 = -399

Factor a perfect square on the left side:
(x + -21)(x + -21) = -399

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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