Question

find the sum of two roots and four of two roots​

Answer 1

Answer:

−8x

3

+21x

2

−20x+5=(x

2

−5x+5)(x

2

−3x+1);

As some of two roots is 4, put x=4−y

The expressions x

2

−5x+5 and x

2

−3x+1 become y

2

−3y+1 and y

2

−5y+5 respectively.

Then, we get (y

2

−3y+1)(y

2

−5y+5)=y

4

−8x

3

+21x

2

−20x+5 which is the original equation.

So, this method fails as we get the same equation after substituting the relation between the roots.