Identifying the Vertex of y=x²+2x: Finding Minimum or Maximum?

Question

Does the parable

y=x2+2x y=x^2+2x

Is there a minimum or maximum point?

Video Solution

Solution Steps

00:00 Does the parabola have a maximum or minimum point?
00:07 The coefficient A of the function is positive, therefore the parabola smiles
00:16 This means the parabola has a minimum point
00:19 And this is the solution to the question

Step-by-Step Solution

To determine whether the quadratic function y=x2+2x y = x^2 + 2x has a minimum or maximum point, we need to examine its structure and calculate the vertex.

Step 1: Identify the structure of the quadratic function.

The given function is y=x2+2x y = x^2 + 2x , which is a standard form quadratic function y=ax2+bx+c y = ax^2 + bx + c where a=1 a = 1 , b=2 b = 2 , and c=0 c = 0 .

Step 2: Calculate the vertex.

The vertex of a quadratic function is given by x=b2a x = -\frac{b}{2a} . Substituting the values of a a and b b into this formula gives:

x=22×1=1 x = -\frac{2}{2 \times 1} = -1 .

Substitute x=1 x = -1 back into the original equation to find the y-coordinate of the vertex:

y=(1)2+2(1)=12=1 y = (-1)^2 + 2(-1) = 1 - 2 = -1 .

Therefore, the vertex is at the point (1,1)(-1, -1).

Step 3: Determine if the vertex is a minimum or maximum.

Since the coefficient a=1 a = 1 is positive, the parabola opens upwards. This means that the vertex represents the lowest point on the graph, which is a minimum point.

Therefore, the solution to this problem is that the parabola has a minimal point.

Answer

Minimal point