Solve 4x^2 20x-39

Question

Simplify the expression

80 x^{3} - 39

Evaluate

4 x^{2} \times 20 x - 39

Solution

More Steps

Evaluate

4 x^{2} \times 20 x

Multiply the terms

80 x^{2} \times x

Multiply the terms with the same base by adding their exponents

80 x^{2 + 1}

Add the numbers

80 x^{3}

80 x^{3} - 39

Show Solution

x = \frac{3 3900}{20}

Alternative Form

x \approx 0.78703

Evaluate

4 x^{2} \times 20 x - 39

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

4 x^{2} \times 20 x - 39 = 0

Multiply

More Steps

Multiply the terms

4 x^{2} \times 20 x

Multiply the terms

80 x^{2} \times x

Multiply the terms with the same base by adding their exponents

80 x^{2 + 1}

Add the numbers

80 x^{3}

80 x^{3} - 39 = 0

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

80 x^{3} = 0 + 39

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

80 x^{3} = 39

Divide both sides

\frac{80 x ^{3}}{80} = \frac{39}{80}

Divide the numbers

x^{3} = \frac{39}{80}

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

3 x^{3} = 3 \frac{39}{80}

Calculate

x = 3 \frac{39}{80}

Solution

More Steps

Evaluate

3 \frac{39}{80}

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

\frac{3 39}{3 80}

Simplify the radical expression

More Steps

Evaluate

380

Write the expression as a product where the root of one of the factors can be evaluated

3 8 \times 10

Write the number in exponential form with the base of 2

3 2^{3} \times 10

The root of a product is equal to the product of the roots of each factor

3 2^{3} \times 310

Reduce the index of the radical and exponent with 3

2310

\frac{3 39}{2 3 10}

Multiply by the Conjugate

\frac{3 39 \times 3 1 0 ^{2}}{2 3 10 \times 3 1 0 ^{2}}

Simplify

\frac{3 39 \times 3 100}{2 3 10 \times 3 1 0 ^{2}}

Multiply the numbers

More Steps

Evaluate

339 \times 3100

The product of roots with the same index is equal to the root of the product

3 39 \times 100

Calculate the product

33900

\frac{3 3900}{2 3 10 \times 3 1 0 ^{2}}

Multiply the numbers

More Steps

Evaluate

2310 \times 3 1 0^{2}

Multiply the terms

2 \times 10

Multiply the terms

20

\frac{3 3900}{20}

x = \frac{3 3900}{20}

Alternative Form

x \approx 0.78703

Show Solution