Find Intervals of Increase for y = x² + 4x + 5

Find the intervals of increase of the function:

y=x2+4x+5 y=x^2+4x+5

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the intervals of increase of the function
00:04 We'll use the formula to find the X value at the vertex
00:07 We'll identify the trinomial coefficients
00:11 We'll substitute appropriate values according to the given data and solve for X
00:18 This is the X value at the vertex point
00:21 The coefficient A is positive, therefore the parabola has a minimum point
00:28 From the graph we'll deduce the intervals of increase of the function
00:34 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

Find the intervals of increase of the function:

y=x2+4x+5 y=x^2+4x+5

2

Step-by-step solution

To solve the problem and find the intervals of increase for the function y=x2+4x+5 y = x^2 + 4x + 5 , we need to follow these steps:

  • Step 1: Calculate the derivative of the function.
  • Step 2: Determine where the derivative is greater than zero.
  • Step 3: Identify the interval where the function is increasing.

Let's perform each step in detail:

Step 1: Calculate the derivative of the function y=x2+4x+5 y = x^2 + 4x + 5 .
The derivative of y y with respect to x x , denoted as y y' , is obtained by differentiating each term:
y=ddx(x2)+ddx(4x)+ddx(5) y' = \frac{d}{dx}(x^2) + \frac{d}{dx}(4x) + \frac{d}{dx}(5) .
This gives y=2x+4 y' = 2x + 4 .

Step 2: Determine where the derivative is greater than zero.
We solve the inequality 2x+4>0 2x + 4 > 0 .
Subtract 4 from both sides: 2x>4 2x > -4 .
Divide by 2: x>2 x > -2 .

Step 3: Identify the interval where the function is increasing.
The function increases on the interval x>2 x > -2 .

Therefore, the solution to the problem is that the function is increasing for x>2 x > -2 .

3

Final Answer

x>2 x>-2

Practice Quiz

Test your knowledge with interactive questions

Note that the graph of the function shown below does not intersect the x-axis

The parabola's vertex is A

Identify the interval where the function is decreasing:

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