Answer:
Slope-intercept form: y = 3x + 5
Slope: 3
y-intercept: 5
Step-by-step explanation:
What is slope-intercept form?
When the equation of a line is written in the slope-intercept form, we can easily identify the slope from the coefficient of x and the y-intercept from the constant.
The slope-intercept form is expressed as y = mx + c, where m is the slope and c is the y-intercept. Note that other textbooks might use y = mx + b instead, but both have the same meaning as both m and b or c will be replaced by a certain value.
Rewriting in slope-intercept form
To rewrite and equation in the slope-intercept form, isolate the y term on the right-hand side of the equation and divide the whole equation by the coefficient of y.
Working
[tex]y - ( - 7) = 3(x - ( - 4))[/tex]
Expand:
[tex]y + 7 = 3(x + 4)[/tex]
[tex]y + 7 = 3x + 12[/tex]
Subtract both sides by 7:
[tex]y = 3x + 12 - 7[/tex]
[tex]\bf{y = 3x + 5}[/tex]
Since the coefficient of y is already 1, we have arrived at our final answer.
Identifying slope
When the equation is in the slope-intercept form, the slope can be identified from the coefficient of x. This refers to the number that comes before x which is multiplied to x.
Thus, the slope is 3.
Identifying the y-intercept
The y-intercept is the value of the constant in the slope-intercept form. This refers to the number that is not attached to any variables.
Hence, the y-intercept is 5.
Note that the y-intercept can also be found by substituting x = 0 into the equation.
Identifying the x-intercept
The x-intercept occurs at y = 0. Since we have the equation of the line, we can substitute y = 0 into the equation to find the value of x when y = 0.
Working
y = 3x + 5
When y = 0,
0 = 3x + 5
3x = -5
Divide both sides by 3:
[tex]x = - \frac{5}{3} [/tex]
Graphing the equation
I have attached the graph as an image. If only a sketch is required, there are 3 pieces of information that needs to be labelled on the graph:
- Axes
- Intercepts
- Equation of the line
Additional resources:
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