Get Answers to all your Questions

header-bg qa

Explain solution for RD Sharma maths Class 12 Chapter 15 Tangents and Normals Exercise Multiple Choice Question, Question 35 maths textbook solution.

Answers (1)

Answer : (d) is the correct option

Hint : \text { Parallel to } x \text {-axis } \Rightarrow y=0

Given : y=x^{3}-12 x+18

Solution :

y=x^{3}-12 x+18                                (1)

Differentiating (1) w.r.t x, we get

\frac{d y}{d x}=3 x^{2}-12

Since it's parallel to x-axis

\begin{aligned} &\frac{d y}{d x}=0 \\ &3 x^{2}-12=0 \\ &x^{2}=4 \\ &x=\pm 2 \end{aligned}

When x=2

\begin{aligned} &y=(2)^{3}-12(2)+18 \\ &=8-24+18 \\ &=2 \end{aligned}

When x = -2

\begin{aligned} &y=(-2)^{3}-12(-2)+18 \\ &=-8+24+18 \\ &=34 \end{aligned}

The points are (2,2) and (-2,34)

Posted by

infoexpert23

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads