y is proportional to x^2. When y=45, x=3. Find a formula for y in terms of x.
If y is proportional to x then you can write y=kx^2 where k is a constant you are trying to find. Then substitute in the values you have been given for x and y. This gives you 45=k(3)^2. Then work to solve this to find k. 45=k(9)k=45/9. Therefore k=5. You can now put your value for k into the formula to give you an answer of y=5x^2.
AP
Related Maths GCSE answers
All answers ▸There are two points 'A' and 'B' on a graph, their coordinates are (0,1) and (10,6) respectively. 1)Find the equation of the line that runs through both of these points.2)Find the equation of a line perpendicular to this through point 'B'.
Fred is reshaping his garden. He decides to make into a right-angled triangle ABC. The length AB= 5m and the length BC= 12 What is the length of AC?
Expand and simplify (-2x+3)(x-6)
Rearrange the following to make c the subject: 11a + 5c = d ( 6 + 2c )