(x^4+5x^2-36)(2x^2+9x-5)=0 solve for the roots. factor both quadratic equations

Hello,

1)
X^4+5x²-36=0
Δ=5²+4*36=169=13²
x²=(-5-13)/2=-9 or x²=(-5+13)/2=4
x^4+5x²-36=(x²+9)(x²-4)=(x-2)(x+2)(x²+9)

2)
2x²+9x-5=0
Δ=9²+4*5*2=121=11²
x=(-9-11)/4=-5 or x=(-9+11)/4=1/2

2x²+9x-5=(x+5)(2x-1)

(x^4+5x^2-36)(2x^2+9x-5)=(x+5)(2x-1)(x+2)(x-2)(x²+9)

The answer would be b

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