Solve (5x+4)(5x-4)

Question

Simplify the expression

25 x^{2} - 16

Evaluate

(5 x + 4) (5 x - 4)

Use (a + b) (a - b) = a^{2} - b^{2} to simplify the product

(5 x)^{2} - 4^{2}

Evaluate the power

More Steps

Evaluate

(5 x)^{2}

To raise a product to a power,raise each factor to that power

5^{2} x^{2}

Evaluate the power

25 x^{2}

25 x^{2} - 4^{2}

Solution

25 x^{2} - 16

Show Solution

x_{1} = - \frac{4}{5}, x_{2} = \frac{4}{5}

Alternative Form

x_{1} = - 0.8, x_{2} = 0.8

Evaluate

(5 x + 4) (5 x - 4)

To find the roots of the expression,set the expression equal to 0

(5 x + 4) (5 x - 4) = 0

Separate the equation into 2 possible cases

5 x + 4 = 0 5 x - 4 = 0

Solve the equation

More Steps

Evaluate

5 x + 4 = 0

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

5 x = 0 - 4

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

5 x = - 4

Divide both sides

\frac{5 x}{5} = \frac{- 4}{5}

Divide the numbers

x = \frac{- 4}{5}

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

x = - \frac{4}{5}

x = - \frac{4}{5} 5 x - 4 = 0

Solve the equation

More Steps

Evaluate

5 x - 4 = 0

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

5 x = 0 + 4

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

5 x = 4

Divide both sides

\frac{5 x}{5} = \frac{4}{5}

Divide the numbers

x = \frac{4}{5}

x = - \frac{4}{5} x = \frac{4}{5}

Solution

x_{1} = - \frac{4}{5}, x_{2} = \frac{4}{5}

Alternative Form

x_{1} = - 0.8, x_{2} = 0.8

Show Solution