(3k-3)(7k+7)=

Solution for (3k-3)(7k+7)= equation:

Simplifying
(3k + -3)(7k + 7) = 0

Reorder the terms:
(-3 + 3k)(7k + 7) = 0

Reorder the terms:
(-3 + 3k)(7 + 7k) = 0

Multiply (-3 + 3k) * (7 + 7k)
(-3(7 + 7k) + 3k * (7 + 7k)) = 0
((7 * -3 + 7k * -3) + 3k * (7 + 7k)) = 0
((-21 + -21k) + 3k * (7 + 7k)) = 0
(-21 + -21k + (7 * 3k + 7k * 3k)) = 0
(-21 + -21k + (21k + 21k2)) = 0

Combine like terms: -21k + 21k = 0
(-21 + 0 + 21k2) = 0
(-21 + 21k2) = 0

Solving
-21 + 21k2 = 0

Solving for variable 'k'.

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

Add '21' to each side of the equation.
-21 + 21 + 21k2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 21k2 = 0 + 21
21k2 = 0 + 21

Combine like terms: 0 + 21 = 21
21k2 = 21

Divide each side by '21'.
k2 = 1

Simplifying
k2 = 1

Take the square root of each side:
k = {-1, 1}