30S Applied Math Mr. Knight – Killarney School Slide 1 Unit: Solving Systems Algebraically Lesson: SLE-L3 Using Spreadsheet Analysis to Solve Linear Systems Learning Outcome B-1 SLE-L3 Objectives: Solve systems of equations using spreadsheets

30S Applied Math Mr. Knight – Killarney School Slide 2 Unit: Solving Systems Algebraically Lesson: SLE-L3 A spreadsheet can be a useful tool when finding a solution for a system of equations. In effect, using spreadsheets is a “guess and check” method that takes advantage of the spreadsheet’s raw computing power…its ability to “guess and check” many, many solutions and highlight the correct one in a very short time. Theory – Guess and Check with a Spreadsheet

30S Applied Math Mr. Knight – Killarney School Slide 3 Unit: Solving Systems Algebraically Lesson: SLE-L3 The Spreadsheet Method uses the following procedure: 1.Solve both of the equations for y. 2.Create 2 formulas in Excel that match the 2 expressions you found. 3.Set up a column of input values (x). 4.Set up 2 columns that calculate your expression values (y). 5.Set up a column that uses a logical test to identify the solution. Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 4 Unit: Solving Systems Algebraically Lesson: SLE-L3 Solve the following system using the Spreadsheet Method. 3x + 4y = -2 2x – y = 17 Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 5 Unit: Solving Systems Algebraically Lesson: SLE-L3 Solve the following system using the Spreadsheet Method. 3x + 4y = -2 2x – y = 17 Solve for y in both equations y = -.75x -0.5 y = 2x -17 Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 6 Unit: Solving Systems Algebraically Lesson: SLE-L3 Solve the following system using the Spreadsheet Method. 3x + 4y = -2 2x – y = 17 Solve for y in both equations y = -.75x -0.5 y = 2x -17 Write spreadsheet equations in B2 and C2 that get x from A2. (Use Row 1 as headings) B2: = -.75*A C2: = 2 *A2 -17 Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 7 Unit: Solving Systems Algebraically Lesson: SLE-L3 Like this Copy the y calculations down. Use a range fill to generate x values. Integer steps usually work. Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 8 Unit: Solving Systems Algebraically Lesson: SLE-L3 Insert this formula in row D and fill down (logical test) Fill your spreadsheet down until you see a solution in D. Theory – Substitution Method

30S Applied Math Mr. Knight – Killarney School Slide 9 Unit: Solving Systems Algebraically Lesson: SLE-L3 Solve the following system using the Spreadsheet Method. 4x - 3y = 2 2x + y = -4 Theory – Substitution Method