Firstly, we find the gradient and y-intercept, to be able to substitute in the values once we have made the equation in linear law form, Y = mX+c
y-intercept = 0.7 (as question states straight line cuts vertical axis at 0.70)
gradient = y2-y1/x2-x1 = 0.7-0 / 0-(-0.233) = 3.00 (3sf)
Now, we will make the equation y = 2-px^q into linear form.
px^q = 2-y
Apply lg to both sides
lg(px^q) = lg(2-y)
expand lg(px^q), and bring the power q to the front
lg(p) + qlg(x) = lg(2-y)
Now, we have an equation in the form Y=mX+c
lg(2-y) = qlg(x) + lg(p)
where lg(2-y) is Y
q is m,
lg(x) is X
and lg(p) is c
Hence, we can find the value of q by subbing in the gradient, and the value of lg(p) by subbing in the y-intercept.
q = 3
lg(p) = 0.7
p = 10^0.7
p = 5.01 (3sf)
Hence, p = 5.01, q=3