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TS EAMCET · Maths · Application of Derivatives

If the slope of the tangent of the curve \(y=a x^3+b x+4\) at \((2,14)\) is 21 , then the values of \(a\) and \(b\) respectively

  1. A \(2,-3\)
  2. B \(3,-2\)
  3. C \(-3,-2\)
  4. D 2, 3
Verified Solution

Answer & Solution

Correct Answer

(A) \(2,-3\)

Step-by-step Solution

Detailed explanation

The curve \(y=a x^3+b x+4\) is passes through (2, 14). \[ \begin{array}{rlrlrl} & \therefore & & 14 & =a(2)^3+b(2)+4 \\ \Rightarrow & & 14 & =8 a+2 b+4 \\ \Rightarrow & & 5 & =4 a+b \end{array} \] Slope of tangent to the curve \(y=a x^3+b x+4\) i.e. \(\frac{d y}{d x}=3 a x^2+b\)…