Solve -9=-2x^2-4x

Question

Solve the quadratic equation

Solve using the quadratic formula

Solve by completing the square

Solve using the PQ formula

x_{1} = - \frac{2 + 22}{2}, x_{2} = \frac{- 2 + 22}{2}

Alternative Form

x_{1} \approx - 3.345208, x_{2} \approx 1.345208

Evaluate

- 9 = - 2 x^{2} - 4 x

Swap the sides

- 2 x^{2} - 4 x = - 9

Move the expression to the left side

- 2 x^{2} - 4 x + 9 = 0

Multiply both sides

2 x^{2} + 4 x - 9 = 0

Substitute a= 2,b= 4 and c= - 9 into the quadratic formula x = \frac{- b \pm b ^{2} - 4 a c}{2 a}

x = \frac{- 4 \pm 4 ^{2} - 4 \times 2 ( - 9 )}{2 \times 2}

Simplify the expression

x = \frac{- 4 \pm 4 ^{2} - 4 \times 2 ( - 9 )}{4}

Simplify the expression

More Steps

x = \frac{- 4 \pm 88}{4}

Simplify the radical expression

More Steps

x = \frac{- 4 \pm 2 22}{4}

Separate the equation into 2 possible cases

x = \frac{- 4 + 2 22}{4} x = \frac{- 4 - 2 22}{4}

Simplify the expression

More Steps

x = \frac{- 2 + 22}{2} x = \frac{- 4 - 2 22}{4}

Simplify the expression

More Steps

x = \frac{- 2 + 22}{2} x = - \frac{2 + 22}{2}

Solution

x_{1} = - \frac{2 + 22}{2}, x_{2} = \frac{- 2 + 22}{2}

Alternative Form

x_{1} \approx - 3.345208, x_{2} \approx 1.345208

Show Solution