Warm Up #4
HW Check – Inverse Worksheet
2.3 - Direct Variation
Direct Variation A linear function defined by an equation of the form y = kx, where k ≠ 0, represents direct variation.
Constant of Variation The Slope, k, is constant. It can be represented at the ratio of
Identifying Direct Variation from a Table Determine whether y varies directly with x. If so, find the constant of variation and write the equations. 1. 2. X Y 2 8 3 12 5 20 X Y 1 4 2 7 5 16
You Try!! Determine whether y varies directly with x. If so, find the constant of variation and write the equations. 1. 2. X Y -1 -2 3 4 6 7 X Y -6 -2 3 1 12 4
Identifying Direct Variation from an Equation For each function, determine whether y varies directly with x. If so, find the constant of variation: y = 4x 2y = 3x y = 2x + 3
You Try!! Determine whether y varies directly with x. If so, find the constant of variation. y = x/2 2y – 1 = x 4x = 8y 7x + 4y = 10
Using Proportions If we know that y varies directly with x. We can use proportions to find missing information. Ex. Suppose y varies directly with x, and x = 3 when y = 7. Find x when y = 21.
You Try! y varies directly with x: If y = 25 when x = 15, find x when y = 10 If y = 30 when x = -3, find y when x = -9
Writing Equations Write an equation of the direct variation that includes the point (10, -15). You Try: Write an equation of the direct variation that includes the point (-40, 16).
Word Problems The Height of an object varies directly with the length of its shadow. A person 6 ft tall casts an 8.5 ft shadow, while a tree casts a 38 ft shadow. How tall is the tree?
Word Problem The amount of a persons paycheck p varies directly with the numbers of hours worked t. For 4o hours of work, the paycheck is $390. Write an equation for the relationship between hours worked and pay.
Direct Variation Worksheet Turn in when you are done! Class work – Group Work Direct Variation Worksheet Turn in when you are done!
Mid-Chapter Review Sheet # 4 – 15 Show all work for credit!! Homework Mid-Chapter Review Sheet # 4 – 15 Show all work for credit!!