Question

if the roots of the quadratic equation 2x2+8x+k=0 are equal them find the value of k.​

Answer 1

Answer:

8

Step-by-step explanation:

Let each roots is 'a'.

In equations written in form of ax² + bx + c = 0,

-b/a is sum of roots ; c/a is product of roots.

Here, as both roots are equal:

= > sum = -(8/2)

= > a + a = - 4

= > 2a = - 4 → a = - 2

Whereas,

= > product = k/2

= > a*a = k/2

= > (-2)(-2) = k/2

= > 4 = k/2

= > 8 = k

Answer 2

ANSWER

2x²+8x+k = 0

Here, a=2, b=8 & c=k

As roots are real & equal, therefore discriminant is equal to 0.

D = 0

D = 0b² -4ac = 0

D = 0b² -4ac = 0b² = 4ac

8² = 4×2×k

64 = 8k

k = 64/8

k = 8