Find the equation of the tangent to y = 2x^2 + 7 at x = 3.

The first step here is to identify what to do. Differentiating the equation y = 2x^2 + 7 will result in dy/dx = 4x. Given that you know that x = 3, you can substitute x = 3 into 4x which gives you 4(3) = 12. Thus, you now know that the gradient is equal to 12 at the point x = 3. However, you are trying to find the equation of the tangent and so you use the equation y = mx + c to calculate the equation. You know that the values are m = 12, x = 3 but y and c are currently unknown. To find the value of y, you substitute x = 3 into the original equation of y = 2x^2 + 7 which gives you y = 25. Plug in the values into y = mx + c to find c and rearrange to find c. c = 25 - 36 = -11. Finally, putting all of these values together results in y = 12x - 11.

Answered by Danielle C. Maths tutor

3141 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

In a cinema, male to female ratio is - 1:3. The ratio of the females, who like popcorn to females who don't like popcorn is 2:1. 10 girls don't like popcorn. How many people are there in the cinema altogether?


blah blah blah


Factorise f(x) = 6x^3 -7x^2 -x +2 = 0


A right-angled triangle has one angle size 60 degrees, and hypotenuse of length 32cm. Calculate the length of the side opposite the 60 degree angle, to 3sf.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences