200x³+36x² -30x+4

600x² +72x -26

600x² +72x -30

600x² +72x -36

f''(x) = 6x + cos x

f''(x) = 3x + 5 - sin x

f''(x) = 6x + 5 + sin x

f''(x) = 6 - cos x

7/2x

-7/2x

-7/2x²

7/2x²

None of these

f''(x) = $-120x^5\cos\left(5x^4\right)$

f''(x) = $-20x^3\sin\left(5x^4\right)$

f''(x) = $-20x^3\cos\left(5x^4\right)\ -60x^2\sin\left(5x^4\right)$

f''(x) = $-400x^6\cos\left(5x^4\right)\ -60x^2\sin\left(5x^4\right)$

$\frac{3}{4}$

$\frac{-3}{4}$

$\frac{1}{4}$

$\frac{-1}{4}$

 $\frac{-x^2}{y^2}$  

 $\frac{-2xy^2+2xy}{y^2}$  

 $\frac{-2xy^3-2x^4}{y^5}$  

 $\frac{-2xy^2-2x^4}{y^4}$