Solve by Factoring m^4-625=0

$m^{4} - 625 = 0$

Step 1

Rewrite $m^{4}$ as ${(m^{2})}^{2}$ .

${(m^{2})}^{2} - 625 = 0$

Step 2

Rewrite $625$ as $25^{2}$ .

${(m^{2})}^{2} - 25^{2} = 0$

Step 3

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = m^{2}$ and $b = 25$ .

$(m^{2} + 25) (m^{2} - 25) = 0$

Step 4

Simplify.

Rewrite $25$ as $5^{2}$ .

$(m^{2} + 25) (m^{2} - 5^{2}) = 0$

Factor.

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = m$ and $b = 5$ .

$(m^{2} + 25) ((m + 5) (m - 5)) = 0$

Remove unnecessary parentheses.

$(m^{2} + 25) (m + 5) (m - 5) = 0$

Step 5

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$m^{2} + 25 = 0$

$m + 5 = 0$

$m - 5 = 0$

Step 6

Set $m^{2} + 25$ equal to $0$ and solve for $m$ .

Set $m^{2} + 25$ equal to $0$ .

$m^{2} + 25 = 0$

Solve $m^{2} + 25 = 0$ for $m$ .

Subtract $25$ from both sides of the equation.

$m^{2} = - 25$

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$m = \pm \sqrt{- 25}$

Simplify $\pm \sqrt{- 25}$ .

Rewrite $- 25$ as $- 1 (25)$ .

$m = \pm \sqrt{- 1 (25)}$

Rewrite $\sqrt{- 1 (25)}$ as $\sqrt{- 1} \cdot \sqrt{25}$ .

$m = \pm \sqrt{- 1} \cdot \sqrt{25}$

Rewrite $\sqrt{- 1}$ as $i$ .

$m = \pm i \cdot \sqrt{25}$

Rewrite $25$ as $5^{2}$ .

$m = \pm i \cdot \sqrt{5^{2}}$

Pull terms out from under the radical, assuming positive real numbers.

$m = \pm i \cdot 5$

Move $5$ to the left of $i$ .

$m = \pm 5 i$

The complete solution is the result of both the positive and negative portions of the solution.

First, use the positive value of the $\pm$ to find the first solution.

$m = 5 i$

Next, use the negative value of the $\pm$ to find the second solution.

$m = - 5 i$

The complete solution is the result of both the positive and negative portions of the solution.

$m = 5 i, - 5 i$

Step 7

Set $m + 5$ equal to $0$ and solve for $m$ .

Set $m + 5$ equal to $0$ .

$m + 5 = 0$

Subtract $5$ from both sides of the equation.

$m = - 5$

Step 8

Set $m - 5$ equal to $0$ and solve for $m$ .

Set $m - 5$ equal to $0$ .

$m - 5 = 0$

Add $5$ to both sides of the equation.

$m = 5$

Step 9

The final solution is all the values that make $(m^{2} + 25) (m + 5) (m - 5) = 0$ true.

$m = 5 i, - 5 i, - 5, 5$

Solve by Factoring m^4-625=0

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