Math Problem Statement

Use the function to evaluate the indicated expressions: f(x) = 7x^2 + 3; evaluate f(x + 2) and f(x) + f(2).

Solution

Let's analyze the given problem and solve it.

The function provided is f(x)=7x2+3f(x) = 7x^2 + 3, and you are asked to evaluate two expressions:

  1. f(x+2)f(x + 2)
  2. f(x)+f(2)f(x) + f(2)

1. Evaluating f(x+2)f(x + 2):

This means we need to substitute x+2x + 2 into the function in place of xx.

f(x+2)=7(x+2)2+3f(x + 2) = 7(x + 2)^2 + 3

First, expand (x+2)2(x + 2)^2:

(x+2)2=x2+4x+4(x + 2)^2 = x^2 + 4x + 4

Now, substitute this back into the function:

f(x+2)=7(x2+4x+4)+3f(x + 2) = 7(x^2 + 4x + 4) + 3

Distribute the 7:

f(x+2)=7x2+28x+28+3f(x + 2) = 7x^2 + 28x + 28 + 3

Combine like terms:

f(x+2)=7x2+28x+31f(x + 2) = 7x^2 + 28x + 31

2. Evaluating f(x)+f(2)f(x) + f(2):

We already know f(x)=7x2+3f(x) = 7x^2 + 3, so now we need to find f(2)f(2).

Substitute 22 into the function:

f(2)=7(2)2+3=7(4)+3=28+3=31f(2) = 7(2)^2 + 3 = 7(4) + 3 = 28 + 3 = 31

So, f(x)+f(2)f(x) + f(2) becomes:

f(x)+f(2)=(7x2+3)+31=7x2+34f(x) + f(2) = (7x^2 + 3) + 31 = 7x^2 + 34

Final answers:

  1. f(x+2)=7x2+28x+31f(x + 2) = 7x^2 + 28x + 31
  2. f(x)+f(2)=7x2+34f(x) + f(2) = 7x^2 + 34

Would you like more details on any of these steps?

Here are five related questions to explore further:

  1. How would the result change if the function were f(x)=7x23f(x) = 7x^2 - 3?
  2. Can you explain why expanding (x+2)2(x+2)^2 results in x2+4x+4x^2 + 4x + 4?
  3. How do you find the vertex of the function f(x)=7x2+28x+31f(x) = 7x^2 + 28x + 31?
  4. What happens to f(x)+f(a)f(x) + f(a) for any value of aa?
  5. How would you solve f(x+h)f(x + h) for a different linear shift like h=3h = 3?

Tip: Always expand binomials like (x+k)2(x + k)^2 carefully by applying the formula (x+k)2=x2+2kx+k2(x + k)^2 = x^2 + 2kx + k^2.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations

Formulas

f(x) = ax^2 + bx + c
Expanding binomials: (x + k)^2

Theorems

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Suitable Grade Level

Grades 9-10