Question

solve the following quadratic

100x^4=400x^3+2100x^2

Answer 1

It's not a quadratic as it stands. However, you can factor it to be

100x^4=400x^3+2100x^2
100x^2 (x^2 - 4x + 21) = 0
100x^2 (x-7)(x+3) = 0
Now just read off the roots