30 3 M 3x 4y = 13 (1) – 2x + 3y = 20 (2) Using elimination: M1 M1 for method of changing equations in order to be Multiply (1) by 2 and (2) by 3: able to eliminate 6x 8y = 26 – 6x + 9y = 60 Subtract the first equation from the second equation: A1 A1 for correct equations M1 M1 for subtracting equations 9y = 60 26 – –8y – 17y = 34 y = 2 A1 A1 cao y Substitute = 2 into (2): M1 M1 for substitution 2x + 3 × 2 = 20 2x = 14 x = 7 Check by substituting both values into A1 A1 cao (1) 3 × 7 4 × 2 = 21 8 = 13 Correct. – – M1 M1 for rearrangement to get one variable as a subject Using substitution: Rearrange one of the equations: A1 A1 cao 2x + 3y = 20 M1 M1 for substitution of the one variable into the other y = equation Substitute into the other equation and A1 A1 cao rearrange. 3x 4() = 13 – + 3x = 13 – + = 3x 13 + = = 119 = 7 x Substitute this into other equation as
30 3x – 4y = 13 (1) 2x + 3y = 20 (2) Using elimination: Multiply (1) by 2 and (2) by 3: 6x – 8y = 26 6x + 9y = 60 Subtract the first equation from the second equation: 9y – –8y = 60 – 26 17y = 34 y = 2 Substitute y = 2 into (2): 2x + 3 × 2 = 20 2x = 14 x = 7 Check by substituting both values into (1) 3 × 7 – 4 × 2 = 21 – 8 = 13 Correct. Using substitution: Rearrange one of the equations: 2x + 3y = 20 y = Substitute into the other equation and rearrange. 3x – 4() = 13 3x – + = 13 3x + = 13 + = = 119 x = 7 Substitute this into other equation as M1 A1 M1 A1 M1 A1 M1 A1 M1 A1 3 M1 for method of changing equations in order to be able to eliminate A1 for correct equations M1 for subtracting equations A1 cao M1 for substitution A1 cao M1 for rearrangement to get one variable as a subject A1 cao M1 for substitution of the one variable into the other equation A1 cao M
Higher_Skills_Algebra_MarkScheme_Edexcel.docx