What substitution should be used to rewrite 4x4 – 21x2 + 20 = 0 as a quadratic equation? u = x2 u = 2x2 u = x4 u = 4x4

Step-by-step explanation:

Alright, lets get started.

The given equation is :

The standard form of quadartic equation is :

For making the given equation into quadtratic, we will change power 4 to power 2

So, lets substitute as u , so

This equation is not like the standard form of quadratic, so we will substitute   ........................  Answer

Hope it will help :)

x=4

step-by-step explanation:

4th option is correct xy=-10

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