the table shows experimental values of variables x and y.
x - 0.25 | 0.5 | 1.0 | 1.5 | 2.5 | 6.0 | 9.0
y - 1.29 | 2.24 | 3.61 | 4.50 | 5.63 | 7.20 | 7.70 |
it is known that x and y are related by an equation of the form xy + ay = bx/ using the vertical axis for y and horizontal axis for y / x, draw a straight line graph of y against y/x for given data. use graph to estimate
(a) value of a and b
(b) value of x for which y = 4x
please help with the second part of the question. thanks. anyway, a = 1.5 and b = 9, for your reference purposes.
My maths is a little rusty, but anyway, here it goes:
xy + ay = bx, so
y(x + a) = bx, and
y = bx / (x + a), and if you substitute the values,
y = 9x / x + 1.5
y = [9 / (x + 1.5)]x (bring the x out so that it is similar to the y = 4x equation)
9 / (x + 1.5) = 4
x = 9/4 - 1.5
x = 0.75
The question asks you to find using the graph.
xy + ay = bx
y= -a (y/x) + b, in which you have found a and b
so for part b
when y=4x, y/x = 4
Since y/x is the X-axis, you draw a vertical line upwards at y/x = 4 (similar to drawing the graph x=4 in a graph with x-axis).
You should be able to estimate the value of y at the intersection point. Divide the estimate by 4 and you get the value of x.
To check if you are correct:
xy + ay = bx
Sub y=4x, a=1.5, b=9
4x^2 + 6x = 9x
4x^2 - 3x = 0
x(4x-3) = 0
Solving, x=0 or x=0.75
Eagle
Owner of Strategic Tuition