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LINEAR RELATIONS REVIEW. Grade 9 Academic Math. Important Terms…. Linear relationship: first differences will be same; produces a straight line when graphed; degree of equation is 1
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LINEAR RELATIONS REVIEW Grade 9 Academic Math
Important Terms… • Linear relationship: first differences will be same; produces a straight line when graphed; degree of equation is 1 • Non-Linear relationship: first differences will not be same; produces a curve when graphed; degree of equation is not 1 • Table of values: is a way of organizing coordinates of the graph; contains X and Y values • First Differences: subtracting the Y - value below the number in the Y column from the number above it; finite differences • Independent variable: the value that determines the dependent variable; X – value
Important Terms… • Dependent variable: value depends on the value of independent variable; Y - value • Direct Variation: doesn’t have flat/initial rate; passes through the origin (0,0) • Partial Variation: have a flat/initial rate; doesn’t passes through the origin (0,0) • Slope: steepness of line; rise over run • X-intercept: set Y as zero; (X,0); on the x - axis • Y-intercept: set X as zero; (0,Y); on the y - axis
Standard Form Ax + By + C = 0 • A, B and C = integers • Any A, B and C = 0, but not A and B at the same time • A is positive • No fractions
Finding Slope… • Find first differences; dividing delta y by the delta x • Counting the rise and the run; in lowest possible fractions; as • Using the formula
Finding X and Y intercepts… • For x – intercept: set Y as zero and solve the equation of line; on the x - axis • For y – intercept: set X as zero and solve the equation of line; on the y - axis
Finding the Equation of a Line… • Slope and a point given: • Plug the value of slope and the point in the linear equation. • Solve for y – intercept (b in linear equation). • Two points given: • Find the slope of line using slope formula. • Substitute the slope and a point in the linear equation. • Solve for y – intercept (b in linear equation).
Special Cases of Lines… Special cases include: • Parallel Lines • Perpendicular Lines • Intersecting Lines • Horizontal Lines • Vertical Lines
Parallel Lines… • Slopes of parallel lines are same • Different y - intercepts • Lines having the same slopes are parallel
Perpendicular Lines… • Slopes of perpendicular lines are negative reciprocal • Lines have slopes that are negative reciprocal, they are perpendicular lines
Intersecting Lines… • Slopes of lines are different from each other • Different y – intercepts • All lines having different slopes intersect each other once on the graph
Horizontal Lines… • Graph: horizontal line, parallel to x - axis • Equation:y = b; as y coordinates stays the same • Slope: m = 0; no rise
Vertical Lines… • Graph: vertical line, parallel to y – axis • Equation: x = a; where a = x – intercept • Slope: m = undefined, no run
Point of Intersection… • Graphing the lines: finding the coordinates of point where lines intersect • Algebraic method, using substitution or elimination: • Balance the equations; let one equation equal the other • Collect x terms on one side and solve for x • Substitute x value in an equation and find y • Put the values in an ordered pair
Rearranging the Equation of Line Equation: ax + by = c • Change into Ax + By + C = 0 (standard form) • Change into y = mx + b (slope and y – intercept) • ax + by = c and Ax + By + C = 0 can be changed into y = mx + b, meaning a linear relation and graph will have a straight line
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Question #1 Which of the following can be used to find the slope of a line? i) ii) iii) • i) only • iii) only • i), ii) only • i), ii) and iii) Answer : i), ii) and iii)
Question #2 Suppose the slope of a line was negative. Select the true statement. • The line is not very steep • The line falls to the right • The line has no x – intercept • The line is very steep Answer : The line falls to the right
Question #3 The student council sells lollipops for 10 cents each. They pay 4 cents for each lollipop and spend $10 to advertise the sale. P represents the student council’s profit, in dollars, and n represents the number of lollipops sold. Which equation represent the profit? • P = 0.06n – 10 • P = 0.06n + 10 • P = 10n + 0.06 • P = 10 + 0.04n Answer : P = 0.06n – 10
Question #4 Which of the following lines has the greatest slope? • 2x + 3y – 10 = 0 • 5x – 3y +15 = 0 • x + 2y – 8 = 0 • x – y + 7 = 0 Answer : 5x – 3y +15 = 0
Question #5 The cost, C, in dollars to print n leaflets is given by the formula C = 35 + 0.03n. What is the cost of printing 900 leaflets? • $27.00 • $35.00 • $37.70 • $62.00 Answer : $62.00
Question #6 The line y = kx + 6 is perpendicular to the line y = ¾ x + 10. Select the value of k. • – 4/3 • - ¾ • -3 • ¾ Answer : - 4/3
Question #7 What are the coordinates of the point of intersection of the lines y = -x + 1 and x = 3? • (2, 3) • (3, 2) • (3, -2) • (-2, 3) Answer : (3, -2)
Question #8 Sam charges a $5 base fee plus $20/h to fix jewellery. In this relationship, what is the dependent variable? • The $5 base fee • The number of hours • The cost • The jewellery Answer : the cost
Question #9 Four points, A(-3, 4); B(-5, -4); C(2, -2) and D(3, 3) lie on an xy- plane and are joined by line segments. Which line segment has a negative slope? • BA • BC • CD • AD Answer : AD
Question #10 Donna has correctly drawn a line on an xy-plane. Her plane is parallel to the line y = x + 1 and has the same y-intercept as the line y = 2x + 6. Which of the following equations represents the line that Donna had drawn? • y = x + 3 • y = -x + 6 • y = x + 6 • y = -x + 3 Answer : y = x +6
Question #11 The points A(-3, -4) and B(6, 2) are placed on an xy-plane. Which statement about the line through AB is not true? • Its x-intercept is 3 • Its slope is positive • Its y-intercept is -2 • Passes through (4, 9) Answer : passes through (4, 9)
Question #12 What is the slope of a line that is perpendicular to 3 – x + 4y = 0? Answer : slope = -4
Question #13 What is the equation of the line that passes through the point (2, 0) and is parallel to the line y = -3x + 4? • y = 3x + 2 • y = 3x + 6 • y = -3x + 2 • y = -3x + 6 Answer : y = -3x + 6
Question #14 Temira needs to rent a car. She considers the following price equations, where C is the total cost, in dollars, and n is the number of days. Which company should she choose if she is planning to rent the car for at least 10 days. • Rentway • Cheapie’s Rental • Cars Cars • Drive Away Answer : Drive Away
Question #15 What is the equation of a line passing through the points (2, 5) and (4, 11)? • y = x – 3 • y = 2x - 1 • y = 3x - 1 • y = 4x – 3 Answer : y = 3x - 1
Question #16 Scientists find that the height of a person, h, in centimeters, is related to the length of the person’s femur bone, f, in centimeters, according to the following formula: h = 69.09 + 2.24f. According to the formula, what is the height of a person with a femur bone of 48.6 cm in length? • 109 cm • 178 cm • 186 cm • 347 cm Answer : 178 cm
Question #17 Determine if the following pair of lines are parallel, perpendicular or neither. Line 1: M (-2, -8); N (3, 5) Line 2: R (0, -9); S (5, 4) Answer : parallel
Question #18 Lori downloads music from Music site, which charges a monthly membership fee plus and an amount for each song downloaded. In February, she was charged $25.30 for 38 songs downloaded. In March, she was charged $23.60 for 21 songs downloaded. Determine the equation of the relationship between numbers of downloads and her monthly bills. Answer : y = 1/10x + 21.50
Question #19 The slope of the line y = 3 is: • 1 • 0 • 3 • Undefined Answer : 0
Question #20 The slope of the line x = 7 is: • 1 • 7 • 0 • Undefined Answer : undefined
Question #21 Classify each relation as a direct variation, partial variation or neither. • d = 45t • y = 2x + 3 • y = 10x • d = 45t + 12
Question #22 Find the equation of the line perpendicular to 3x + y – 2 = 0 and having the same x-intercept as the line 5x – 9y + 45 = 0. Write the equation in standard form. Answer : y = 1/3x + 3
Question #23 To purchase a fishing license, it costs $25/year plus a one-time $5 fee for processing the application. In this relationship, what is the independent variable? • The $5 fee for processing • The number of years • The cost • The $25/year fee Answer : the number of years
Question #24 Bob is the editor of the school yearbook. He is in charge of collecting money from students for yearbooks. He collects $35 per student. The money he collects depends on the number of students who buy yearbooks. • What are the two variables? • Is this a direct or partial variation?
Question #25 Find the point of intersection for the following system algebraically. y = -2x – 8 y = - 2/3x – 4 Answer : P.O.I is (-3, -2)
Question #26 Find the equation of a line parallel to 2x + 5y = 1, with the same y-intercept as x – 4y = 8. Answer : y = -2/5x - 2