The x-intercept from the equation y= (x-a)√(x-b), x = a or x = b
From the x= b+1, where b is constant, therefore only x = a is true.
Now, dy/dx = √(x-b) + (x-a)/(2√(x-b)), where x - b = 1, and x - a = 0
dy/dx = 1
Therefore the gradient of the curve is 1