5.3 Differentiating polynomials Quiz

1. Differentiate $f(x)=3x^4-2x$.

• A. $12x^3-2$
• B. $12x^4-2x$
• C. $3x^3-2$
• D. $12x^3$

2. Differentiate $y=x^2-\frac{5}{x^2}$.

• A. $2x+\frac{10}{x}$
• B. $2x-\frac{10}{x^3}$
• C. $2x+\frac{10}{x^{3}}$
• D. $2x-10x^{-1}$

3. Find the gradient of $y=x^3-4x+1$ at $x=-2$.

• A. $-8$
• B. $16$
• C. $17$
• D. $8$

4. $f(x)=2x^3-9x^2$. For which $x$ is $f'(x)=0$?

• A. $x=0$ only
• B. $x=0$ or $x=3$
• C. $x=3$ only
• D. $x=0$ or $x=9$

5. $C(x)=x^2+\frac{100}{x}$ is a cost in AED for $x$ items. Find $C'(5)$.

• A. $6$
• B. $10$
• C. $-10$
• D. $14$