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The function f is defined for all real values of x as f(x) = c + 8x - x^2, where c is a constant. Given that the range of f is f(x) <= 19, find the value of c. Given instead that ff(2) = 8, find the possible values of c.

We know -x^2 has a maximum point of 0 at x=0, and -x^2 dominates the behaviour of f. We complete the square on this eqn, so we have f(x) = -(x - 4)^2 + 16 + c. We note that g(x) = -(x - 4)^2 has a maximum...

Answered by Sanmay K. • Maths tutor

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Let X be a normally distributed random variable with mean 20 and standard deviation 6. Find: a) P(X < 27); and b) the value of x such that P(X < x) = 0.3015.

a) 27 is higher than the mean. So we can simply calculate the z value. z = (27 - 20)/6 ≈ 1.17. Using the table in the formula booklet, we find that P(Z < 1.17) = 0.8790, so P(X ...

Answered by Maximillian H. • Maths tutor

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How do I find the stationary points on the curve y = f(x) = x^3+6x^2-36x?

When trying to find stationary points, the first thing you should think about is differentiating. At a stationary point, the gradient of a curve or function is equal to zero. Therefore if we differentiate...

Answered by Luke S. • Maths tutor

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Given y=x^2(1+4x)^0.5, show that dy/dx=2x(5x+1)/((1+4x)^0.5)

You have to differentiate the equation y=x^2(1+4x)^0.5 with respect to x to get dy/dx and thereby prove the result in the question. An equation composed of the product of two x terms can be differentiated...

Answered by Alistair G. • Maths tutor

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