Online Course Discussion Forum

MCIII Algebra 3.30

 
 
JinTina的头像
MCIII Algebra 3.30
JinTina - 2024年01月12日 Friday 14:04
 

Hello,

I need some help on this question. After squaring both sides, rearranging, then squaring again:

x^4-8x^2+x+12=0. 

I tried rational root, grouping, and double cross method to find the roots, but I'm not sure how to get the roots.

I also tried the "reversing role" method, by letting a=4 and trying to solve the equation for a, but I then I didn't find a way to factor it and after plugging in the quadratic formula I got a quartic again but now in terms of a and even more complicated.

Thanks,

Tina Jin

 
LinXilong的头像
Re: MCIII Algebra 3.30
LinXilong - 2024年01月12日 Friday 22:14
 

The left hand side is equal to ( x^2 - x - 3 ) (x^2 + x -4 ).

JinTina的头像
Re: MCIII Algebra 3.30
JinTina - 2024年01月14日 Sunday 08:47
 

Oh I messed up on the double cross method, thank you for your response!