Differentiate y = (3x + 1)^3 and evaluate dy/dx at x = 1.

Answer and explanation

Correct answer: B. 144

  1. Step 1: Apply the chain rule: dy/dx = 3 x 3 x (3x + 1)^2.
  2. Step 2: At x = 1 the inner expression equals 4.
  3. Step 3: dy/dx = 3 x 3 x 4^2 = 144.
Answer
144.
Why not the others: '48' omits the inner derivative 3 from the chain rule; '64' evaluates y instead of dy/dx; '576' does not lower the exponent by one.

Practise more Algebra, Functions, Geometry and Probability.

Free questions with an explanation for every one, and full timed Državna Matura (Bosnia & Herzegovina) mock tests.

All Algebra, Functions, Geometry and Probability questionsTake a mock test

More Algebra, Functions, Geometry and Probability questions