Answer:
y = 2x + 3
Step-by-step explanation:
Hi there!
We are given the points (-1, 1) and (3,9) which belong to a line
We want to write the equation of the line in slope-intercept form
Slope-intercept form is given as y=mx+b, where m is the slope and b is the y intercept
First, let's find the slope of the line
The slope (m) can be found using the formula [tex]\frac{y_2-y_1}{x_2-x_1}[/tex], where [tex](x_1, y_1)[/tex] and [tex](x_2, y_2)[/tex] are points
Let's label the values of the points before we start, to avoid confusion and mistakes
[tex]x_1 = -1\\y_1=1\\x_2=3\\y_2=9[/tex]
Now substitute into the formula (note: the formula has SUBTRACTION, and we have NEGATIVE numbers, so we'll end up subtracting a negative)
m = [tex]\frac{y_2-y_1}{x_2-x_1}[/tex]
m = [tex]\frac{9-1}{3--1}[/tex]
Simplify
m=[tex]\frac{9-1}{3+1}[/tex]
m=[tex]\frac{8}{4}[/tex]
Divide
m = 2
The slope of the line is 2
We can substitute this as m in y=mx+b.
y = 2x + b
Now we need to find b
As the equation passes through the point (-1, 1) and (3, 9), we can use either point to help solve for b.
Taking (3, 9) for example:
substitute 3 as x and 9 as y.
9 = 2(3) + b
Multiply
9 = 6 + b
Subtract 6 from both sides
3 = b
Substitute 3 as b in the equation
y = 2x + 3
Hope this helps!
Topic: finding the equation of the line
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