Question

If the normal to the curve y = f(x) at the point (3, 4) makes an angle 3π/4 with the positive

x- axis, then f′(3) is equal to

• A. –1
• B. – $\frac{3}{4}$
• C. $\frac{4}{3}$
• D. 1

Answer 1

Answer: (D)

1

Answer 2

According to the given condition

– $\frac{1}{f^{'}(3)}$= tan 3π/4 = –1

⇒ f′(3) = 1