Solve 5x^2 - 4x - 672 = 0

Question

Solve the quadratic equation

Solve by factoring

Solve using the quadratic formula

Solve by completing the square

x_{1} = - \frac{56}{5}, x_{2} = 12

Alternative Form

x_{1} = - 11.2, x_{2} = 12

Evaluate

5 x^{2} - 4 x - 672 = 0

Factor the expression

More Steps

Evaluate

5 x^{2} - 4 x - 672

Rewrite the expression

5 x^{2} + (56 - 60) x - 672

Calculate

5 x^{2} + 56 x - 60 x - 672

Rewrite the expression

x \times 5 x + x \times 56 - 12 \times 5 x - 12 \times 56

Factor out x from the expression

x (5 x + 56) - 12 \times 5 x - 12 \times 56

Factor out - 12 from the expression

x (5 x + 56) - 12 (5 x + 56)

Factor out 5 x + 56 from the expression

(x - 12) (5 x + 56)

(x - 12) (5 x + 56) = 0

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

x - 12 = 0 5 x + 56 = 0

Solve the equation for x

More Steps

Evaluate

x - 12 = 0

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

x = 0 + 12

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

x = 12

x = 12 5 x + 56 = 0

Solve the equation for x

More Steps

Evaluate

5 x + 56 = 0

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

5 x = 0 - 56

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

5 x = - 56

Divide both sides

\frac{5 x}{5} = \frac{- 56}{5}

Divide the numbers

x = \frac{- 56}{5}

Use \frac{- a}{b} = \frac{a}{- b} = - \frac{a}{b} to rewrite the fraction

x = - \frac{56}{5}

x = 12 x = - \frac{56}{5}

Solution

x_{1} = - \frac{56}{5}, x_{2} = 12

Alternative Form

x_{1} = - 11.2, x_{2} = 12

Show Solution