Presentation on theme: "Homework Answers: Workbook page 2"— Presentation transcript:
1 Homework Answers: Workbook page 2 N, W, Z, Q, R 13) Assoc. (X) 25) 8x – y – 3I,R 14) Comm. (X) 26) -4cI, R 15) Add. Inverse 27) -5r – 58sW, Z, Q, R 16) Mult. Inverse 28) 4a + 1Q, R 17) Distributive 29) -12 – 8x + 6yZ, Q, R 18) Add. Identity 30) 13yZ, Q, R 19) -0.4, 2.5 or 5/2 31) (110t + 100) miQ, R 20) 1.6, or -5/8 32) false; counter-Comm. (+) 21) 11/16, -16/ example:Assoc. (+) 22) -5 5/6, 6/ (1/5) is not >Mult. Identity 23) 3x (1/4)Distributive 24) -4a-16b
2 Solving Equations Worksheet K = ) x = 19H = ) x = 7D = -16/13 or ) x = -1/15 or .0667J = -63/2 or ) k = 18/23 or.7826X = ) r = -5X = ) g = -16
3 Solving Equations with the Variable on Both Sides Objectives:to solve equations with the variable on both sides.to solve equations containing grouping symbols.A.1 Solve linear equations in one variable.A.1 Apply these skills to solve practical problems.A.3 Justify steps used in solving equations.
4 To solve equations with variables on both sides: 1. Use the addition property to move all variables to one side of the equal sign.2. Solve the equation by working the problem backwards.
5 Let’s see a few examples: 1) 6x - 3 = 2x + 13-2x x4x - 3 = 134x = 16x = 4Be sure to check your answer!6(4) - 3 =? 2(4) + 13=?21 = 21
12 Solving Formulas: What it means to solve To solve for x would mean to get x by itself on one side of the equation, with no x’s on the other side. (x = __ )Similarly, to solve for y would mean to get y by itself on one side of the equation, with no y’s on the other side. (y = __ )
13 The DO-UNDO chart 1) Solve the equation -5x + y = -56 for x. Ask yourself:What is the first thing being done to x,the variable being solved for?x is being multiplied by DO UNDO· yWhat is being done next? y ÷(-5)y is being added to -5x.
14 Show all of your work!First, subtract y from both sides of the equation.Next, divide by -5.This process actually requires LESS WORK than solving equations in one variable Ex: -5x + y = -56- y -y-5x = yx = y = 56 + y
15 Let’s try another: Ex: Solve 2x - 4y = 7 for x. +4y + 4y2x = 7 + 4yx = 7 + 4y2This fraction cannot be simplified unless both terms in the numerator are divisible by 2.Complete the do-undo chart.DO UNDO· y- 4y ÷ 2To solve for x:First add 4yThen divide by 2
16 Another example: Solve a(y + 1) = b for y. DO UNDO + 1 ÷ a · a - 1 To solve for y:First divide by aThen subtract 1a(y + 1) = ba ay + 1 = bay = b - 1
17 Here’s a tricky one! Solve 3ax - b = d - 4cx for x. First, we must get all terms with x together on one side.Add 4cx to both sidesAdd b to both sidesNext, use the distributive property to factor x out of the two terms on the left.Now, x is being multiplied by (3a + 4c). To undo this, divide both sides by (3a + 4c).3ax - b = d - 4cx+4cx cx3ax - b + 4cx = d+b b3ax + 4cx = d + bx(3a + 4c) = d + b(3a + 4c) (3a + 4c)x = d + b(3a + 4c)
18 Try a few on your own. Solve P = 1.2W for W. H2 Solve P = 2l + 2w for l.Solve 4x - 3m = 2mx - 5 for x.
19 The answers: DO UNDO · 1.2 · H2 ÷ H2 ÷ 1.2 W = PH2 1.2 DO UNDO · 2 -2w l = P - 2w2Subtract 2mx, thenAdd 3m to get4x - 2mx = 3m - 5x(4 - 2m) = 3m - 5Divide by (4 - 2m)x = 3m - 54 - 2m