Question

If-5 is a root of 2x2+px-15=0 and root of p(x2+x)+k=0 are equal,than find the value of p and k

Answer 1

As -5 is root of 2x2+px-15, substitute -5 in the given expression gives the value of p.

2(-5)2+p(-5)-15=0

50-5p-15=0

35 = 5p

p = 7

Now going to second equation p(x2+x)+k and substituing -5 for x and 7 for p gives

7((-5)2+(-5)) + k = 0

7(25-5) + k = 0

k = -140

So p=7 and k = -140