Ch. 5 Review Answers - Head-Royce

Chapter 51. Write the equation from the Ch. 4 Garfield graph in slope-intercept form.Y = -500 x + 8000 (check the scale on each axis!!)2. In point-slope form, find the equation of the line that passes through the points (3, 5)and (–3, 9).Slope:9 ! 5 4 2= = !! 3 ! 3 ! 6 32y – 5 = ! (x – 3) OR y – 9 =3equations?3. Convert your answer from #2 into standard form.Do the algebra work to get y by itself: 2x + 3y = 212! (x - -3) why could there be two possible34. Write the equation for the line that is perpendicular to y = –6x + 4 and passes throughthe point (12, 5).Perpendicular slope to -6 will be 1 . The easiest way to write an equation is to use point6slope form now, b/c I know a point and the slope: Y – 5 = 1 (x – 12)6OR, I could find b to use slope intercept form:If I plug in the point (12,5) with a slope of 1 6 :y = mx + b5 = 1 6 (12) + b5 = 2 + bb = 3The equation is y = 1 6 x + 3.Elisa’s parents just gave her an iPod Touch for her birthday (nice parents!), and she’sready to fill it up with content. Songs cost $1 and TV shows cost $2. Her friends gaveher a $50 iTunes gift card (nice friends!).

5. Write an equation in standard form for the amount of songs and TV shows that shecan buy with her gift card. Be sure to define your variables.X = # of songs she buysY = # of shows she buysSo 1x or just x is the cost of all the songs she buys, and 2y is the cost of all the shows shebuysx + 2y = 506. Write the equation from #5 in slope-intercept form. Make songs your independentvariable (input) and TV shows your dependent variable (output).If TV shows is the dependent variable, that’s my “y”, so I’m trying to solve the eqn in #5for y.2y = 50 – xDivide all by 2xy = 25 ! OR 21y = ! x + 2527. From the equation that you wrote in #6, what is the y-intercept? What does it mean inthis situation? Try sketching and labeling a quick graph to help you think about this.The y-intercept is 25. It is the number of shows she can buy if she buys no songs.# of TV shows she buys# of songs she buys

8. Which form of linear equations do you find most useful? Why?Answer will depend.