Question

If -5 is a toot of quadratic equation 2x2+px-15=0 and the quadratic equation p(x2+x)k has equal roots find k

Answer 1

Answer:

Step-by-step explanation:

-5 is the root of equation

2x²+px-15=0

Put x = -5

2(-5)²+p(-5)-15=0

50-5p-15=0

35-5p=0

-5p = -35

p=7

p(x²+x)+k

Put value of p

7x²+7x+k

If the roots are real and equal then their discriminant is equal to 0

Discriminant=b²-4ac

0=b²-4ac

7²-4×7×k=0

49-28k=0

-28k=-49

k=-49/-28

k=7/4