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+3
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What is the larger root of the equation x^2-10x+21=0

 

What does the "larger root" mean?

GAMEMASTERX40  May 19, 2018
edited by GAMEMASTERX40  May 19, 2018
 #1
avatar+945 
+4

Hey GM!

 

We can factor this quadratic:

 

\(x^2-10x+21=(x-7)(x-3)=0\)

 

I'm not going to explain how to factor the quadratic, but you can learn here:

 

https://www.mathsisfun.com/algebra/factoring-quadratics.html

 

We then get x = 7 and x = 3. 

 

7 is the larger root, 

 

I hope this helped,

 

Gavin

GYanggg  May 19, 2018
 #2
avatar+3171 
+3

First, we take to move 21 to the other side. 

x^2-10x=-21

x=3, one root

But, \(\boxed{x=7}\) is also another root, which is larger than x=3.

smileysmiley

tertre  May 19, 2018
 #3
avatar+945 
+3

Hey tertre, I don't understand how you got 3 just from moving 21 to the other side. 

 

I'm pretty sure that's not how you solve a quadratic. 

 

Are you just guess and checking?

GYanggg  May 19, 2018
 #4
avatar+3171 
+3

Yes, I just guess and check!

Your solution is beautiful!

smileysmiley

tertre  May 19, 2018
 #5
avatar+945 
+3

I that case, I guess that works too!

 

Nice job!

GYanggg  May 19, 2018
 #6
avatar+3171 
+3

Thank you, Gavin!

smileysmiley

tertre  May 20, 2018

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