y is proportional to x^2 and that when y = 75, x = 5. Find a formula for y in terms of x and find y when x=3

In a proportional equation, you represent the factor of proportionality as k. In this case it means that y=kx^2. In the question you're given a number for both y and x. Sub these in in order to solve for k. This would mean that 75=k(5)^2. This leads to 75=25k. This leads to k=3. The formula for y in terms of x is therefore y=3x^2.Now that you have k you can sub in the value given to you in the question for x in order to find y. This leads you to have y=3(3)^2. y=3(9)y=27.

KI
Answered by Kesem I. Maths tutor

3788 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How do you complete the square? example: x^2 + 8x + 13=0


ABC is a right-angled triangle (B being the right angle). Is AB=12 and BC=9, What is Angle A? (3.s.f.)


Solve the simultaneous equations. x^2 + 2y=9, y-x=3


Which of these fractions is the largest - 33/56 ,4/7, 9/21, 6/14


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