Problem 26 - Algebra 1

Question

Evaluate the function when \(x=2, x=0,\) and \(x=-3\). $$ h(x)=\frac{3}{4} x-4 $$

Step-by-Step Solution

Answer

The values of the function \(h(x) = \frac{3}{4} x-4\) at \(x = 2, 0, -3\) are respectively \(h(2) = -2.5\), \(h(0) = -4\), and \(h(-3) = -6.25\).

Step 1: Substitute \(x = 2\) into \(h(x)\)

Substitute \(x = 2\) into \(h(x) = \frac{3}{4} x-4\). This gives \(h(2) = \frac{3}{4} \cdot 2 - 4\). When we perform the multiplication and subtraction, we get \(h(2) = 1.5 - 4 = -2.5\).

Step 2: Substitute \(x = 0\) into \(h(x)\)

Substitute \(x = 0\) into \(h(x) = \frac{3}{4} x-4\). This gives \(h(0) = \frac{3}{4} \cdot 0 - 4\). When we perform the multiplication and subtraction, we get \(h(0) = 0 - 4 = -4\).

Step 3: Substitute \(x = -3\) into \(h(x)\)

Substitute \(x = -3\) into \(h(x) = \frac{3}{4} x-4\). This gives \(h(-3) = \frac{3}{4} \cdot -3 - 4\). When we perform the multiplication and subtraction, we get \(h(-3) = -2.25 - 4 = -6.25\).

Key Concepts

Linear Functions

In the world of algebra, linear functions are like the straight-line paths that connect two points. They are elegant in their simplicity and are defined by an equation of the form:
\[ y = mx + b \]
Here, \(m\) represents the slope of the line, which tells us how steep or flat our academic journey is. A higher slope means a steeper climb or descent, while a zero slope indicates a flat path. On the other hand, \(b\) is the y-intercept, symbolizing the starting point of our journey on the graph's vertical axis.

The function presented in the exercise, \(h(x) = \frac{3}{4} x - 4\), is a classic example of a linear function. Its slope is \(\frac{3}{4}\), suggesting a gentle upward slope for positive x-values. The y-intercept, in this case, is -4, indicating that our linear journey crosses the y-axis below sea level.

Function Substitution

Function substitution is like taking a road trip with set destinations. The destinations here are the specific values of \(x\) we're plugging into the function. It's a way of evaluating how the function behaves at certain points.

To substitute a value for \(x\) in a function like \(h(x) = \frac{3}{4} x - 4\), we replace every instance of \(x\) with the given number and carry out the arithmetic operations. It’s just like setting the GPS to a new location: once the input changes, so does our output. In the step-by-step solution provided, for example, when we set our course to \(x = 2\), we find that our function's output gives us \(h(2) = -2.5\). This specific process of substitution helps us understand how the function behaves or 'what the scenery looks like' at that specific point.

Algebraic Expressions

Algebraic expressions are the phrases and sentences of the algebra world. They’re made up of variables, numbers, and operations that come together to express a mathematical idea. In our exercise, \(\frac{3}{4} x - 4\) is an algebraic expression that represents a linear function.

Understanding how to work with these expressions is essential for mastering algebra. Think of it like learning a new language: we need to know the grammar (operations), the vocabulary (variables and constants), and how to put them together to form meaningful sentences (expressions). When we encounter a new expression or equation, we can manipulate it using algebraic rules to simplify or solve for unknown values—just as we do when playing with words to create eloquent poetry or a persuasive argument.