Answer:
The value of x is 5 units ⇒ C
Explanation:
In the given figure
∵ Δ ABC is a right triangle at vertex B
∵ AC is its hypotenuse
∵ BD ⊥ AC
∴ (BD)² = AD × DC
∵ BD = 10 units
∵ AD = x units
∵ DC = 4x units
→ Substitute them in the rule above
∴ (10)² = x × 4x
∴ 100 = 4x²
→ Divide both sides by 4
∵
=

∴ 25 = x²
→ Take √ for both sides
∴ 5 = x
∴ The value of x is 5 units