Given a quadratic equation, find a value of

Jazmyn Holden

Jazmyn Holden

Answered question

2022-03-25

Given a quadratic equation, find a value of a such that the quadratic equation would have one root less than -1 and another greater than 1.

Answer & Explanation

Roy Brady

Roy Brady

Beginner2022-03-26Added 19 answers

Step 1
It means this polynomial has two real roots and that 1 separates the roots.
The discriminant
Δ=(2a3)24(a2+a+1)(a5)>0
Under this hypothesis, there is a high-school theorem on the separation of roots:
Here, the leading coefficient is a2+a+1, which is always positive (its roots are the complex cubic roots of unity). So the separating condition is merely
p(1)=a2+a+1+2a3+a5=a2+4a7<0.
Note that if p(1)<0, the quadratic polynomial necessarily has tow real roots;, so the first condition is automatically satisfied.
zevillageobau

zevillageobau

Beginner2022-03-27Added 13 answers

Step 1
The hint.
Let f(x)=(a2+a+1)x2+(2a3)x+a5.
Thus, since
a2+a+1=(a+12)2+34>0,
we need to solve the following inequality:
f(1)<0

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?