If -5 is a root of the quadratic equation 2x^{2}+px-15=0

Michelle Arroyo

Michelle Arroyo

Answered question

2021-11-30

If -5 is a root of the quadratic equation 2x2+px15=0 and the quadratic equation p(x2+x)+k=0 has equal roots. Find the value of k

Answer & Explanation

Camem1937

Camem1937

Beginner2021-12-01Added 10 answers

Step 1 
2x2+px15=0 
b5 is the quadratic equation's root, it will satisfy the condition.
2(5)2+p(5)15=0 
5015=5p 
35=5p 
p=7 
Now p=7 
p(x2+x)+k=0 has equal roots 
7(x2+x)+k=0 
7x2+7x+k=0 
b roots are equal then 
b24ac=0 
(7)24×7×k=0 
49=28k 
4928=k 
k=74

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