Question

If the discriminant of the quadratic equation 4x² + px + 25 = 0 is 0, find the value of p, given that p is a natural number.

• A. 10
• B. 20
• C. 30
• D. -20

Answer 1

The correct option is B

20

Comparing the given quadratic equation with the standard form, we get

a = 4, b = p and c = 25.

Discriminant, D = $b^2-4\times a\times c$

$\Rightarrow$ $p^2-4\times 4\times 25=0$

$\Rightarrow$ $p^2-400=0$

$\Rightarrow$ p = 20, –20

Since,p is a natural number, we get

p = 20