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3 years ago

Solve the following system using substitution x+4y=21 4x-y=16

1 answer:

5 0

x+4y=21
4x-y=16

Isolate one of the variables
x + 4y = 21
subtract 4y from both sides
x = -4y + 21

Plug that into the other equation
4x - y = 16
4(-4y + 21) - y = 16
-16y + 84 - y = 16
combine like terms
-17y + 84 = 16
subtract 84 from both sides
-17y = -68
divide both sides by -17
y = 4

Plug that into the equation
x+4y=21
x + 4(4) = 21
x + 16 = 21
subtract 16 from both sides
x = 5

Hope this helps!

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Find the slope of the line through the points (−3, 6) and (2, 6).

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Answer:

There wouldn't be a slope. It would be 0/5

Step-by-step explanation:

$\frac{6-6}{2+3}$

6 - 6 = 0

2 + 3 = 5

0/5 isn't a slope.

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How do you write the equation of a line (in slope intercept form) with three given points?

Mrrafil [7]

With even just two points, you can find the equation of a line in slope-intercept form.

Slope-intercept form: $y=mx+b$ where $m$ is the slope and $b$ is the y-intercept

1) Solve for the slope ( $m$ )

The equation to solve for the slope is $m=\frac{y_2-y_1}{x_2-x_1}$ when the two points are $(x_1,y_1)$ and $(x_2,y_2)$ . Plug the coordinates of these points into the equation and solve for $m$ .

Then, plug $m$ into $y=mx+b$ .

1) Solve for the y-intercept ( $b$ )

Then, take any of the given points and plug it into $y=mx+b$ along with the slope. Isolate $b$ to get the y-intercept. Then, plug both m and b back into $y=mx+b$ to get your final equation.

I hope this helps!

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