Direct Variation
Direct Variation is a linear function defined by an equation of the form y = _ _ ?
What is y = kx
Where "K" cannot be equal to zero !
A trend line that shows the relationship between two sets of data most accurately.
What is "trend line"
9-2
What is 1/81
What is the simplified form of the expression?
(4z5)(9z-12)
What is (36) / (z7) ?
What is the factored form of
x2 + 8x + 15
What is
(x + 3)(x + 5)
Write the following equation in y=kx
7y = 2x
What is the constant of variation?
What is y = 2/7 (x)
Constant of variation is k = 2/7
Draw an example of:
1) Positive correlation
2) Negative correlation
3) No correlation
Check dry erase boards.
(-3.6)0
What is 1?
Simplified form
(2a)(9b4)(3a2)
What is 54a3b4
What is the factored form
x2 - 11x + 24
What is
(x - 3)(x - 8)
Write the following equation in y = kx form
3y + 4x = 8
What is the constant of variation?
What is y = -4/3(x) + 8/3
You cannot write the equation in the form y=kx.
It is not a direct variation.
What is the approximate weight of a 7-month old panda? Based on the data for the panda's weight for the first 12 months, predict the weight of a 18-month old panda.
x = age in months
y = weight in pounds
(1,2.5) (2, 7.6) (3, 12.5) (4, 17.2) (6, 24.3)
(8, 37.9) (10, 49.2) (12, 54.9)
Check dry erase boards
What is the simplified form of the following expression?
5a3b-2
What is (5a3) / b2 ?
Simplified form
(n4)7
What is n28
What is the factored form of
x2 +2x -15
What is
(x - 3)(x + 5)
Suppose "y" varies directly with "x", and y=35 when x=5. What direct variation equation relates to x and y?
What is y=7x
(page 109)
Jean sales
For this list, make a scatter plot of the data. Describe the type of correlation the scatter plot makes.
x = Average price in dollars
y = number of jeans sold
(21, 130) (28, 112) (36, 82) (40, 65)
Check graphing calculators and dry erase boards
What is the simplified form?
(1) / (x-5)
What is X5 ?
What is the simplified form
(m2n4) / (m5n3)
What is n/m3
The area of a rectangle is given by the trinomial
x2 - 2x - 35
What are the possible dimensions of the rectangle?
What is
(x + 5)(x - 7)
Space Exploration
Weight on Mars "y" varies directly with weight on Earth "x". The weight of the science instruments onboard of The Phoenix Mars LAnder on Earth and Mars are shown below.
Weight on Mars: 50 pounds
Weigh on Earth: 130 pounds
What is an equation that relates weight, in pounds, on Earth "x" and weight on Mars "y"?
What is y=0.38x
The equation y=0.38x gives the approximate weight "y" on Mars, in pounds, of an object that weights "x" pounds on Earth.
(page 109)
Gasoline Purchases
For this table, make a scatter plot of the data. Describe the type of correlation the scatter plot makes.
x = dollars spent
y = number of gallons bought
(10, 2.6) (11, 3) (9, 2.4) (8, 2.2) (13, 3.5)
How many gallons can you buy with $76 ?
Check graphing calculator and dry erase boards
What is the value of 3s3t-2 for s=2 and t=-3?
What is 24/9 ?
What is the simplified form
(2x6/y4)-3
What is y12/8x18
What is the factored form
x2 + 6xy - 55y2
What is
(x - 5y)(x + 11y)