Zeroes of polynomial are √2 and -√2
Factor will be
(x-√2)(x+√2)
=(x²-2)
now, dividing the polynomial with this factor,
x²-2)2x⁴ +7x³ -19x² -14x +30(2x²+7x-15
2x⁴ -4x²
- +
0 7x³-15x²-14x+30
7x³ -14x
- +
0 -15x 0 +30
-15x +30
+ -
0 0
So, the factors are (x²-2)(2x²+7x-15)
=(x²-2)(2x²+10x -3x -15)
=(x²-2)[2x(x+5)-3(x+5)]
=(x²-2)(x+5)(2x-3)
so, other zeroes are -5 and 3/2