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Please help me with this question. Algebra 2 is hard!!

Please help me with this question. Algebra 2 is hard!!-example-1
User InkGolem
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Answer:

  • domain: {x ∈ ℝ : x ≤ 5}
  • range: {y ∈ ℝ : y ≤ -1}

Explanation:

Domain

The domain of a function is the set of x values for which the function is defined. Here, the domain is limited by the values of x that make the square root defined. That is, the expression under the radical cannot be negative:

-3x +15 ≥ 0

15 ≥ 3x . . . . . . add 3x

5 ≥ x . . . . . . . . divide by 3

x ≤ 5 . . . . . . . . put x on the left (swap sides)

The rest of the notation in the domain expression simply says x is a real number.

domain: {x ∈ ℝ : x ≤ 5} . . . . . . matches the first choice

__

Range

The range of a function is the set of values that f(x) can have. We know the square root can be zero or any positive number. When it is zero, f(x) = -1.

When it is a positive number, that value is multiplied by -4 and added to -1, so f(x) is a number more negative than -1. Then the range of the function is all numbers -1 and below:

range: {y ∈ ℝ : y ≤ -1} . . . . . . matches the last choice

_____

Comment on domain/range problems

When working domain and range problems, it works well to have a good understanding of the domain and range limitations of the functions we usually work with: polynomials, square root, logarithm, trig functions, exponential functions. Domain and range problems generally involve combinations of these or ratios of combinations of these.

User Ethan Yang
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