3.4 – Slope & Direct Variation
Direct Variation:
3.4 – Slope & Direct Variation Direct Variation: y = kx
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation)
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation) Reads:
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation) Reads: “y varies directly with x.”
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation) Reads: “y varies directly with x.” –Direct Variation Equations ALWAYS go through the origin!!!
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation) Reads: “y varies directly with x.” –Direct Variation Equations ALWAYS go through the origin!!! –Constant of Variation = Slope
3.4 – Slope & Direct Variation Direct Variation: y = kx (k = constant of variation) Reads: “y varies directly with x.” –Direct Variation Equations ALWAYS go through the origin!!! –Constant of Variation = Slope, so k = m!
Ex. 1 Graph y = 4x
1)Write the slope as a ratio.
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 =
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0)
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0)
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point.
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point. 4
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point. 1 4
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point. 1 4
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point. 4)Draw line through points 1 4
Ex. 1 Graph y = 4x 1)Write the slope as a ratio. 4 = 4 1 2)Graph (0,0) 3)Use slope to find next point. 4)Draw line through points 1 4
Ex. 2 Graph y = -½x
1)Write the slope as a ratio. 2)Graph (0,0) 3)Use slope to find next point. 4)Draw line through points
Ex. 2 Graph y = -½x 1)Write the slope as a ratio. 2 2)Graph (0,0) 3)Use slope to find next point. 4)Draw line through points 2
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve.
Ex.3 If y = 8 when x= 4, find y when x= 5.
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation:
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4)
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2, so y = 2x
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2, so y = 2x 2)Plug in given value, solve for missing!
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2, so y = 2x 2)Plug in given value, solve for missing! y = 2x
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2, so y = 2x 2)Plug in given value, solve for missing! y = 2x y = 2(5)
Write a direct variation equation that relates x and y. Assume that y varies directly with x. Then solve. Ex.3 If y = 8 when x= 4, find y when x= 5. 1)Write equation: y = kx 8 = k(4) 8 = 4k k = 2, so y = 2x 2)Plug in given value, solve for missing! y = 2x y = 2(5) y = 10
Ex.4 If y = 36 when x = 6, find x when y = 42
1)Write equation: 2)Plug in given value, solve for missing!
Ex.4 If y = 36 when x = 6, find x when y = 42 1)Write equation:y = kx 36 = k(6) 36 = 6k k = 6, so y = 6x 2)Plug in given value, solve for missing! y = 6x 42 = 6x 7 = x