3x^2+9=21

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Solution for 3x^2+9=21 equation: 


Simplifying
3x2 + 9 = 21

Reorder the terms:
9 + 3x2 = 21

Solving
9 + 3x2 = 21

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-9' to each side of the equation.
9 + -9 + 3x2 = 21 + -9

Combine like terms: 9 + -9 = 0
0 + 3x2 = 21 + -9
3x2 = 21 + -9

Combine like terms: 21 + -9 = 12
3x2 = 12

Divide each side by '3'.
x2 = 4

Simplifying
x2 = 4

Take the square root of each side:
x = {-2, 2}

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