Which equation represents the line that passes through the points 7,8 and 3,-4

Sagot :

Answer:

y = 3x - 13

Step-by-step explanation:

We are given the points (7,8) and (3,-4)

We want to write an equation of the line that passes through those 2 points.

There are 3 ways to write the equation of the line:

  • Slope-intercept form, which is y=mx+b, where m is the slope and b is the value of y at the y intercept.
  • Standard form, which is ax+by=c, where a, b, and c are free integer coefficients, but a and b cannot be 0 and a cannot be negative.
  • Point-slope form, which is [tex]y-y_1=m(x-x_1)[/tex], where m is the slope and [tex](x_1 ,y_1)[/tex] is a point.

Although while any one of these options work, the most common way is to use slope-intercept form, so let's do it that way.

First, we need to find the slope of the line.

The slope (m) can be found using this 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.

Even though we already have 2 points, let's label their values to avoid any confusion.

[tex]x_1=7\\y_1=8\\x_2=3\\y_2=-4[/tex]

Now substitute these values into the formula.

m=[tex]\frac{y_2-y_1}{x_2-x_1}[/tex]

m=[tex]\frac{-4-8}{3-7}[/tex]

Subtract.

m=[tex]\frac{-12}{-4}[/tex]

Divide.

m = 3

The slope of the line is 3.

Here is the equation of the line so far:

y = 3x + b

We now need to find b.

As the equation passes through  (7,8) and (3,-4), we can use either one of the points to help us solve for b.

Taking (7,8) for instance:

Substitute 7 as x and 8 as y in the equation.

8 = 3(7) + b

Multiply

8 = 21 + b

Subtract 21 from both sides

-13 = b

Substitute -13 as b in the equation.

y = 3x - 13

Topic: finding the equation of the line

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A line is a one-dimensional shape that is straight, has no thickness, and extends in both directions indefinitely. The equation of the line that passes through the points (7,8) and (3,-4) is y=3x-13.

What is the equation of a line?

A line is a one-dimensional shape that is straight, has no thickness, and extends in both directions indefinitely. The equation of line is given by,

y =mx + c

where,

x is the coordinate of the x-axis,

y is the coordinate of the y-axis,

m is the slope of the line, and

c is the y-intercept.

The slope of the equation will be,

Slope, m = (-4-8)/(3-7) = -12/-4 = 3

Substitute one of the points in the equation of the line,

-4 = 3(3) + C

C = -13

Hence, the equation of the line that passes through the points (7,8) and (3,-4) is y=3x-13.

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