Intermediate November 2020 Unit 2 Q18
18. Solve the following simultaneous equations using an algebraic (not graphical) method.
\[\begin{aligned} 3x - 2y &= 14 \\ 7x + 3y &= 25 \end{aligned}\]You must show all your working. [4]
| Scheme | Marks | Comments |
|---|---|---|
| Method to eliminate variable e.g. equal coefficients with appropriate addition or subtraction. | M1 | No marks for trial and improvement. Allow 1 error in one term, not the term with equal coefficients. |
| First variable found, x = 4 or y = −1. | A1 | C.A.O. |
| Substitute to find the 2nd variable. | m1 | F.T. their ‘1st variable’. |
| Second variable found | A1 | Award no marks for unsupported correct answers. |