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1.Write the equation in point-slope form with the given slope of -2 and passes through the point (4,-5)

2. Write the equation in slope-intercept form of the line parallel to y=4x-2 and passes through (4,6)

3. Write the equation in slope-intercept form with the given slope of 3 and passes through (-1,1)

4. Write the equation in slope-intercept form of the line perpendicular to 2x-7y=1 and passes through (0,-4)


Sagot :

1.

The equation in point-slope form:  y - y₁ = m(x - x₁)

slope:  m = -2

point:   (4, -5)   ⇒   x₁ = 4, y₁ = -5

Therefore, the equation of the line in point-slope form:

y + 5 = -2(x - 4)

2.

The equation in slope-intercept form:   y = mx + b

Parallel lines has the same slope, so:

y = 4x + 2     ⇒    a = 4

If a line passes through the point (x₁, y₁) then the equation y = mx + b is true.

(4, 6)  ⇒   x₁ = 4, y₁ = 6  

So:   6 = 4·4 + b  ⇒   b = -10

Therefore the equation:  

y = 4x - 10

3.

a = 3

(-1, 1)  ⇒   x₁ = -1, y₁ = 1  

So:   1 = 3·(-1) + b  ⇒   b = 4

The equation:  

y = 3x + 4

4.

The product of slopes of perpendicular lines is -1.

2x - 7y = 1    ⇒  7y = -2x + 1   ⇒  y = -²/₇x + ¹/₇

-²/₇×m = -1    ⇒   m = ⁷/₂

(0, -4)  ⇒   x₁ = 0, y₁ = -4  

-4 = ⁷/₂·0 + b   ⇒   b = -4

The equation:

y = ⁷/₂x - 4