Solve 2k^2-4k=126

Question

Solve the quadratic equation

Solve by factoring

Solve using the quadratic formula

Solve by completing the square

k_{1} = - 7, k_{2} = 9

Evaluate

2 k^{2} - 4 k = 126

Move the expression to the left side

2 k^{2} - 4 k - 126 = 0

Factor the expression

More Steps

Evaluate

2 k^{2} - 4 k - 126

Rewrite the expression

2 k^{2} - 2 \times 2 k - 2 \times 63

Factor out 2 from the expression

2 (k^{2} - 2 k - 63)

Factor the expression

More Steps

Evaluate

k^{2} - 2 k - 63

Rewrite the expression

k^{2} + (7 - 9) k - 63

Calculate

k^{2} + 7 k - 9 k - 63

Rewrite the expression

k \times k + k \times 7 - 9 k - 9 \times 7

Factor out k from the expression

k (k + 7) - 9 k - 9 \times 7

Factor out - 9 from the expression

k (k + 7) - 9 (k + 7)

Factor out k + 7 from the expression

(k - 9) (k + 7)

2 (k - 9) (k + 7)

2 (k - 9) (k + 7) = 0

Divide the terms

(k - 9) (k + 7) = 0

When the product of factors equals 0,at least one factor is 0

k - 9 = 0 k + 7 = 0

Solve the equation for k

More Steps

Evaluate

k - 9 = 0

Move the constant to the right-hand side and change its sign

k = 0 + 9

Removing 0 doesn't change the value,so remove it from the expression

k = 9

k = 9 k + 7 = 0

Solve the equation for k

More Steps

Evaluate

k + 7 = 0

Move the constant to the right-hand side and change its sign

k = 0 - 7

Removing 0 doesn't change the value,so remove it from the expression

k = - 7

k = 9 k = - 7

Solution

k_{1} = - 7, k_{2} = 9

Show Solution