+208 You must minimise the function. To do this, you must allow the derivative of the function to be equal to zero:
\(f(x) = 2x^2 -10x + 15\)
\(f'(x) = 4x - 10\)
Now let the fucntion equal zero and find the value of x at this point:
\(0 = 4x - 10\)
\(10 = 4x\)
\(10/4 = 2.5 = x\)
Sub this back into the initial function to find the lowest point of this parabola:
\(f(2.5) = 2(2.5)^2 - 10(2.5) + 15\)
This coincidentally comes to a minimum of 2.5
Hope this is right :)
