Math  /  Algebra

QuestionA line passes through the points (1,2)(-1,2) and (3,18)(3,18). Write its equation in slope-intercept form.
Write your answer using integers, proper fractions, and improper fractions in simplest form. \square

Studdy Solution

STEP 1

What is this asking? We need to find the equation of a line that goes through two specific points and write it in a way that shows the slope and where the line crosses the y-axis. Watch out! Don't mix up the xx and yy coordinates when calculating the slope!
Also, remember that "simplest form" means no common factors in the fractions.

STEP 2

1. Calculate the Slope
2. Determine the Y-intercept
3. Write the Equation

STEP 3

Alright, let's **kick things off** by finding the slope of our line!
Remember, the slope tells us how steep the line is.
It's the **rise over run**, or the change in yy divided by the change in xx.

STEP 4

We've got two points: (1,2)(-1, 2) and (3,18)(3, 18).
Let's label them!
Let (1,2)(-1, 2) be (x1,y1)(x_1, y_1) and (3,18)(3, 18) be (x2,y2)(x_2, y_2).

STEP 5

The **slope formula** is: m=y2y1x2x1 m = \frac{y_2 - y_1}{x_2 - x_1} Let's **plug in** our values: m=1823(1) m = \frac{18 - 2}{3 - (-1)}

STEP 6

**Simplify** the numerator and denominator: m=163+1=164 m = \frac{16}{3 + 1} = \frac{16}{4}

STEP 7

Now, let's **simplify the fraction**: m=164=4 m = \frac{16}{4} = 4 So, our **slope** is m=4m = 4!
Awesome!

STEP 8

Next up, the **y-intercept**!
This is the point where our line crosses the y-axis.
We can find it using the **slope-intercept form** of a linear equation: y=mx+b y = mx + b where mm is the slope (which we just found!) and bb is the y-intercept.

STEP 9

We can **plug in** one of our points and the slope to solve for bb.
Let's use the point (1,2)(-1, 2): 2=4(1)+b 2 = 4(-1) + b

STEP 10

**Simplify** and **solve for** bb: 2=4+b 2 = -4 + b Add 4 to both sides: 2+4=4+4+b 2 + 4 = -4 + 4 + b 6=b 6 = b So, our **y-intercept** is b=6b = 6!

STEP 11

We've got our **slope** (m=4m = 4) and our **y-intercept** (b=6b = 6).
Now, we just need to **plug them into** the slope-intercept form: y=mx+b y = mx + b

STEP 12

**Substitute** the values: y=4x+6 y = 4x + 6 And there we have it!

STEP 13

The equation of the line in slope-intercept form is y=4x+6y = 4x + 6.

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