Find all the zeroes of the polynomial

Question

2x^4+7x^3-19x^2-14x+30 , if two of its zeroes are root2 and -root2?

Answer 1

(x-√2)(x+√2) = x^2-2

(2x^4+7x^3-19x^2-14x+30)/(x^2-2) = 2x^2+7x-15

Now you can factor that to find the other two roots