Solve 5x^3=3x 7 - ScanMath

Question

Solve the equation

x_{1} = - \frac{105}{5}, x_{2} = 0, x_{3} = \frac{105}{5}

Alternative Form

x_{1} \approx - 2.04939, x_{2} = 0, x_{3} \approx 2.04939

Evaluate

5 x^{3} = 3 x \times 7

Multiply the terms

5 x^{3} = 21 x

Add or subtract both sides

5 x^{3} - 21 x = 0

Factor the expression

x (5 x^{2} - 21) = 0

Separate the equation into 2 possible cases

x = 0 5 x^{2} - 21 = 0

Solve the equation

More Steps

Evaluate

5 x^{2} - 21 = 0

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

5 x^{2} = 0 + 21

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

5 x^{2} = 21

Divide both sides

\frac{5 x ^{2}}{5} = \frac{21}{5}

Divide the numbers

x^{2} = \frac{21}{5}

Take the root of both sides of the equation and remember to use both positive and negative roots

x = \pm \frac{21}{5}

Simplify the expression

More Steps

Evaluate

\frac{21}{5}

To take a root of a fraction,take the root of the numerator and denominator separately

\frac{21}{5}

Multiply by the Conjugate

\frac{21 \times 5}{5 \times 5}

Multiply the numbers

\frac{105}{5 \times 5}

When a square root of an expression is multiplied by itself,the result is that expression

\frac{105}{5}

x = \pm \frac{105}{5}

Separate the equation into 2 possible cases

x = \frac{105}{5} x = - \frac{105}{5}

x = 0 x = \frac{105}{5} x = - \frac{105}{5}

Solution

x_{1} = - \frac{105}{5}, x_{2} = 0, x_{3} = \frac{105}{5}

Alternative Form

x_{1} \approx - 2.04939, x_{2} = 0, x_{3} \approx 2.04939

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