Online Course Discussion Forum

algebra 2020 summer

 
 
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algebra 2020 summer
by Danny huang - Thursday, August 6, 2020, 3:45 PM
 

For 7.28, we need to solve the value a  that have the maximum root. In your answer key, how do you know the maximum root is cube root of 2 over 2? You did not make any explanation , so I am confused. Is Okay. Is there anywhere they might have established that fact about the roots?

Thanks! 

 
Picture of James Shi
Re: algebra 2020 summer
by James Shi - Friday, August 7, 2020, 10:43 AM
 

I don't think I'm in the same class as you, but I think I had the same question on my homework. Try rewriting the equation as a quadratic with $a$ as the variable and use the condition that $a$ is a real number.

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Re: algebra 2020 summer
by Dr. Kevin Wang - Sunday, August 9, 2020, 11:40 PM
 

This is for the MC II-A course.

Question 7.28 is referring to question 7.8: 

Let $a$ be a real number, and the equation $x^2+a^2x+a=0$ has real roots for $x$. Find the maximum possible root $x$.

The solution to Question 7.8 is in the lecture video, and also available in the book.  Question 7.28 is an additional question based on that.

To James Shi: Good! This is the same question in MC III.  There are multiple practices with this technique and I hope everyone learns the mathematical ideas behind it.