Direct Variation and Slope Review

What is the slope?

-4/1

What is the slope of this graph?

10/1

What is the slope of this graph?

30/2

What is the slope of this graph?

5/3

What is it called when the line is slanting down?

Decreasing/Negative

What is it called when the line is slanting up?

Increasing/Positive

What is it called when the line is vertical?

Slope is undefined

What is it called when the line is horizontal?

Slope is zero

What are the steps for this problem: Given that x and y vary directly, and that y = (Blank) when x = (Blank), find y when x = (Blank).

Step one- Find k Step two- Write the equation Step three- Plug in the given variable to solve for the unknown

What are the steps of Direct Variation?

Step one- Find k Step two- write the equation

What are the steps to determine if the line is direct variation?

Step one- Is it a straight line? Does it go thru the origin? If yes to both it is direct variation. Step two- Find the slope Step three- Write the equation y = kx where k is the slope

What are the steps of finding x or y?

Step one- Write the equation. Step two- Plug in the given variable and solve for the unknown.

Given that x and y vary directly, write the equation relating x and y if x = 3 when y = 24.

Step one- k= 24/3= 8 Step two- y= 8x

Given that x and y vary directly, and that y = 3000 when x = 250, find y when x = 300.

Step one- k= 3000/250 = 12 Step two- y= 12x Step three- y= 12*300= 3600

Given that y varies directly with x. If x=12 then y=8. What is the equation for Direct variation?

Step one- k= 8/12= 2/3 Step two- y= 2/3x

If y varies directly with x, and the constant of variation is k = ½ , find y when x = 30.

Step one- y= 1/2*30 Step two- 15= 1/2*30

Is this an example of direct variation?

Yes

Is this table an example of direct variation?

Yes

What is the equation to use for finding 'k'?

k=y/x

How do you find Direct Variation from a table?

y/x If all are same answer the table is and example of Direct Variation

What is the equation to determine slope?

y1 - y2 / x1 - x2

What is the equation for Direct Variation?

y=kx