A Maths

Jasmine ngjiamin SG

Q 1) 2x² + 5xy + 2y² = 0

x² - y² = 1

find x and y.

Q 2) 3x + 2y - z = 4

5x - 7z = 26

express y in terms of x and y.

wee_ws SG

Hi Jasmine,

Q2 looks problematic when it is to express y in terms of x and y.

For Q1,

1. factorise 1st equation;

2. obtain possible relationships between x and y;

3. use the relationships in 2nd equation.

Thanks.

Cheers,
Wen Shih

wee_ws SG

Hi,

Q1 (no linear equation) & Q2 (3 unknowns) may not be appropriate as questions in Additional Maths, if we refer to the syllabus statement:

1.4 Simultaneous equations in two unknowns.
Include:
- solving simultaneous equations with at least one linear equation, by substitution;
- expressing a pair of linear equations in matrix form and solving the equations by inverse matrix method.

Thanks.

Cheers,
Wen Shih

Jasmine ngjiamin SG

ok thks^^

wee_ws SG

Hi,

If the original question 1 were to assess higher-order thinking, one may reword it, in Cambridge sense, as follows:

The real unknowns x and y satisfy the equations

2x^2 + 5xy + 2y^2 = 0 and x^2 - y^2 = 1.

(i) By factorising the first equation, find two possible relationships between x and y.

(ii) Explain why only one relationship is valid and use it to find the possible values of x and y.

Thanks.

Cheers,
Wen Shih

wee_ws SG

Hi,

Q1 can be used as a question in A-level H2 Maths, since complex roots are involved.

Thanks.

Cheers,
Wen Shih