Chapter 2: Problem 64
Find the value of \(y\) if a linear function goes through the following points and has the following slope: \((10, y),(25,100), m=-5\)
Short Answer
Expert verified
The value of \( y \) is 175.
Step by step solution
01
Understand the Linear Equation
A linear function can be represented as \( y = mx + c \), where \( m \) is the slope, and \( c \) is the y-intercept. We are given the slope \( m = -5 \) and two points: \((10, y)\) and \((25, 100)\).
02
Use Point-Slope Form
The point-slope form of a line is given by \( y - y_1 = m(x - x_1) \). We can use the point \((25, 100)\) to apply this formula. So, \( y - 100 = -5(x - 25) \).
03
Simplify the Equation
Substitute the coordinates of the first point into the equation to find \( y \). First, simplify the expression: \( y - 100 = -5(x - 25) \) becomes \( y - 100 = -5x + 125 \).
04
Solve for Y
To find \( y \) when \( x = 10 \), substitute \( x = 10 \) into the equation: \( y = -5(10) + 225 \). This simplifies to \( y = -50 + 225 = 175 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
The slope-intercept form of a linear equation is a way of expressing the equation of a line. In this form, the equation is written as:\( y = mx + c \).Understanding this form is crucial for working with linear equations. Here:
In the original exercise, once the line's equation is simplified, it can be compared to this form to easily identify the characteristics of that specific linear function.
- \( m \) is the slope of the line, representing how steep the line is. In simpler terms, it tells us how much \( y \) changes for a unit change in \( x \).
- \( c \) is the y-intercept, the point where the line crosses the y-axis. When \( x = 0 \), \( y \) is equal to \( c \).
In the original exercise, once the line's equation is simplified, it can be compared to this form to easily identify the characteristics of that specific linear function.
Point-Slope Form
The point-slope form is another convenient way to express the equation of a line, especially when you know a point on the line and the slope. The equation takes the form of:\( y - y_1 = m(x - x_1) \).Here, \((x_1, y_1)\) is a known point on the line, and \( m \) is the slope. This form directly ties in a specific point, allowing you to form the line's equation even if the y-intercept is unknown.
- A major benefit of the point-slope form is that it simplifies when you have a specific point and a slope, allowing for easy substitution into the equation.
- This form is ideal for initial computation before transitioning to the slope-intercept form for further interpretation.
Solving for a Variable
Solving for a variable means isolating it on one side of the equation to find its value. It's a basic yet essential skill in algebra that has wide applications.In the exercise, we had to solve for \( y \) when the line passed through specific points and had a defined slope.
- Start by substituting known values into the equation derived from a particular form (like point-slope or slope-intercept).
- Rearrange the equation to make the variable of interest the subject of the formula.
- Perform operations step-by-step to isolate the variable. These might include addition, subtraction, multiplication, division, or a combination of those.