The general answer is :

$$x = \sqrt[3]{\frac{14}{5}}$$

Principal real root:

$$x_1 = 1.40945975$$

Complex roots:

$$x_2 = −0.704729873+1.22062795i$$

$$x_3 = −0.704729873−1.22062795i$$

We are given the equation:

$$\frac{8 \times 7}{5x} = 4x^2$$

Step 1: Simplify the Left-Hand Side

Compute 7x8:

$$\frac{56}{5x} = 4x^2$$

Step 2: Cross Multiply

Multiply both sides by $5x$ to eliminate the fraction:

$$56 = 4x^2 \cdot 5x$$

$$56 = 20x^3$$

Step 3: Solve for $x$

Divide both sides by 20:

$$\frac{56}{20} = x^3$$

$$\frac{14}{5} = x^3$$

Step 4: Take the Cube Root

$$x = \sqrt[3]{\frac{14}{5}}$$

This is the exact solution. Approximating the cube root numerically:

$$x \approx \sqrt[3]{2.8} \approx 1.4$$

Principal real root:

$$x_1 = 1.40945975$$

Complex roots:

$$x_2 = −0.704729873+1.22062795i$$

$$x_3 = −0.704729873−1.22062795i$$