How can we determine stationary points by completing the square?

Suppose we have completed the square on y=ax^2+bx+c and attained y=a(x+p)^2+q, where a,b,c,p,q are real numbers with 'a' not equal to zero and p,q can be expressed in terms of a,b,c. For a>0 we have a minimum point, where x takes a value such that a(x+p)^2+q is smallest, giving x= -p and hence y=q. For a<0, we have a maximum point, where x takes a value such that a(x+p)^2+q is biggest, also giving x= -p and hence y=q. 

HY

Related Maths A Level answers

All answers ▸

What is a Binomial distribution and when, in an exam, should I use it?


The point P lies on a curve with equation: x=(4y-sin2y)^2. (i) Given P has coordinates (x, pi/2) find x. (ii) The tangent to the curve at P cuts the y-axis at the point A. Use calculus to find the coordinates of the point A.


Differentiate y = x^3 + 2x^2 + 4x + 7


using the substitution u=6-x^2 integrate (x^3)/(6-x^2)^1/2 with respect to x, between 1 and 2