Solve -7(-6k^4)-4k

Question

Simplify the expression

42 k^{4} - 4 k

Evaluate

- 7 (- 6 k^{4}) - 4 k

Solution

More Steps

Evaluate

- 7 (- 6)

Multiplying or dividing an even number of negative terms equals a positive

7 \times 6

Multiply the numbers

42

42 k^{4} - 4 k

Show Solution

Factor the expression

2 k (21 k^{3} - 2)

Evaluate

- 7 (- 6 k^{4}) - 4 k

Multiply the numbers

More Steps

Evaluate

- 7 (- 6)

Multiplying or dividing an even number of negative terms equals a positive

7 \times 6

Multiply the numbers

42

Evaluate

42 k^{4}

42 k^{4} - 4 k

Rewrite the expression

2 k \times 21 k^{3} - 2 k \times 2

Solution

2 k (21 k^{3} - 2)

Show Solution

Find the roots

k_{1} = 0, k_{2} = \frac{3 882}{21}

Alternative Form

k_{1} = 0, k_{2} \approx 0.456671

Evaluate

- 7 (- 6 k^{4}) - 4 k

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

- 7 (- 6 k^{4}) - 4 k = 0

Multiply the numbers

More Steps

Evaluate

- 7 (- 6)

Multiplying or dividing an even number of negative terms equals a positive

7 \times 6

Multiply the numbers

42

42 k^{4} - 4 k = 0

Factor the expression

2 k (21 k^{3} - 2) = 0

Divide both sides

k (21 k^{3} - 2) = 0

Separate the equation into 2 possible cases

k = 0 21 k^{3} - 2 = 0

Solve the equation

More Steps

Evaluate

21 k^{3} - 2 = 0

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

21 k^{3} = 0 + 2

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

21 k^{3} = 2

Divide both sides

\frac{21 k ^{3}}{21} = \frac{2}{21}

Divide the numbers

k^{3} = \frac{2}{21}

Take the 3 -th root on both sides of the equation

3 k^{3} = 3 \frac{2}{21}

Calculate

k = 3 \frac{2}{21}

Simplify the root

More Steps

Evaluate

3 \frac{2}{21}

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

\frac{3 2}{3 21}

Multiply by the Conjugate

\frac{3 2 \times 3 2 1 ^{2}}{3 21 \times 3 2 1 ^{2}}

Simplify

\frac{3 2 \times 3 441}{3 21 \times 3 2 1 ^{2}}

Multiply the numbers

\frac{3 882}{3 21 \times 3 2 1 ^{2}}

Multiply the numbers

\frac{3 882}{21}

k = \frac{3 882}{21}

k = 0 k = \frac{3 882}{21}

Solution

k_{1} = 0, k_{2} = \frac{3 882}{21}

Alternative Form

k_{1} = 0, k_{2} \approx 0.456671

Show Solution