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.

DC
Answered by Danielle C. Maths tutor

3800 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Rearrange the following equation to make T the subject: (3T+A)/2 = B


Solve 4(x-5)=18


John ran a race at his school. The course was measured at 450m correct to 2sf and his time was given at 62 econds to the nearest second. Calculate the difference between his maximum and minimum possible average speed. Round you answer to 3sf.


Bhavin, Max and Imran share 6000 rupees in the ratios 2 : 3 : 7. Imran then gives 3/5 of his share of the money to Bhavin. What percentage of the 6000 rupees does Bhavin now have? Give your answer correct to the nearest whole number.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning