Direct Variation
vocab - use notes on page 4-7
vocab - use notes on page 4-7
Direct Variation exists when a relationship is ______.
Proportional
The value of y varies directly with x. If x=4 and y= 36, what is K?
k=9
Write the equation for a line in slope-intercept form, when the slope is 1/2 and the y-intercept is 3.
y = 1/2x+3
Find the slope of a perpendicular line given:
y=4/5x + 19
-5/4
What is exactly the same on two lines that are parallel?
The slope
What is the equation for direct variation?
Y=KX
y=243
Find the slope for a line parallel to
y=4x - 2
4
Find the slope of a perpendicular line given:
y= 5x + 20
-1/5
True or False.
Lines that are parallel intersect?
False, they NEVER intersect.
What does the k stand for in the direct variation equation?
Y=KX
the constant
The value of y varies directly with x. If y=40 when x=20, find the value of x when y=80
x=40
Write an equation of a line parallel to the line y=-4x+10 and has a y - intercept of (0,-8)
y=-4x-8
Write an equation in slope-intercept form for a line perpendicular to y=3/4x +1 and contains the point (0,3). Hint first find the slope
y=-4/3x + 3
Lines that are parallel to the y axis have a slope of _____.
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How do you know if a situation is proportional?
It will be a straight line and have k = y/x as a constant
The cost of a smoothie at Fruit Mixers is proportional to the number of ounces ordered. If a 16-oz smoothie costs $3.36, find the cost of a 20-oz smoothie.
$4.20
Write an equation for a line parallel to y=1/4x - 9 and passes through the point (8,1).
y=1/4x-1
Write an equation for a line that is perpendicular to y=6x + 4 and passes through the point (12,-5). Hint find the slope, then use the point-slope form.
y=-1/5x -3
The slopes of perpendicular lines are ________ with the _______ sign.
reciprocals
opposite
Direct variation can also say that the value of y "varies directly" with ____.
x
The distance a roadrunner travels, y, is directly proportional to x, the time in seconds. A roadrunner travels 34 meters in 4 seconds. How fast would the roadrunner run for 51 meters?
6 seconds
Determine the slope of a line that is parallel to the x-axis and passes through the point (6, -8). Then write the equation of the parallel line.
slope = 0
equation is y=-8
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A line perpendicular to the x-axis will be ______ and have an _______ slope.
vertical
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