10 questions · Form 4 Additional Mathematics Bab 3: Systems of Equations
Find the coordinates of the turning/intersection point where the line y = 4x - 4 touches the curve y = x² cleanly as a tangent.
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Find the coordinates of the turning/intersection point where the line y = 4x - 4 touches the curve y = x² cleanly as a tangent.
Answer: A
Equate y: x² = 4x - 4 => x² - 4x + 4 = 0 => (x - 2)² = 0 => x = 2. Then y = (2)² = 4. Touch point is (2, 4).
2. If a straight line y = mx + c is tangent to a curve x² + y² = 5, what must be the value of the discriminant B² - 4AC when the line is substituted into the curve?
Answer: C
A line being tangent to a curve means it touches the curve at exactly one point (two equal real roots), which corresponds to B² - 4AC = 0.
3. When solving simultaneous equations involving one linear and one non-linear equation, what is the best first step?
Answer: B
The standard substitution method requires expressing one variable as the subject from the linear equation first, then substituting it into the non-linear equation.
4. If x - y = 3 and x² + y² = 29, find the value of xy.
Answer: A
Square (x - y = 3): (x - y)² = 9 => x² - 2xy + y² = 9. Substitute x² + y² = 29: 29 - 2xy = 9 => 2xy = 20 => xy = 10.
5. Find the points of intersection between the line y = 2x - 1 and the parabola y = x² - 4.
Answer: A
Equate y: x² - 4 = 2x - 1 => x² - 2x - 3 = 0 => (x - 3)(x + 1) = 0 => x = 3 or x = -1. When x = 3, y = 5. When x = -1, y = -3. Points are (3, 5) and (-1, -3).
6. Solve the system: 2x + y = 7 and x² + xy = 12. What is one of the possible values for x?
Answer: A
Substitute y = 7 - 2x into x² + xy = 12: x² + x(7 - 2x) = 12 => x² + 7x - 2x² = 12 => -x² + 7x - 12 = 0 => x² - 7x + 12 = 0 => (x - 3)(x - 4) = 0 => x = 3 or x = 4.
7. Two numbers have a sum of 12 and a product of 35. Find the larger number.
Answer: A
x + y = 12 and xy = 35 => x(12 - x) = 35 => x² - 12x + 35 = 0 => (x - 7)(x - 5) = 0. Numbers are 7 and 5. Larger is 7.
8. Which of the following equations is a linear equation in three variables?
Answer: C
A linear equation in three variables must have each variable raised to the power of 1 without product terms like xy. Thus, 3x - 4y + 2z = 9 is linear.
9. Solve the non-linear system: x - 2y = 1 and x² - 4y² = 5. Find x + 2y.
Answer: A
Use difference of squares: x² - 4y² = (x - 2y)(x + 2y) = 5. Given x - 2y = 1, we get 1(x + 2y) = 5 => x + 2y = 5.
10. If three planes in 3D space intersect along a common straight line, how many solutions does the system of three linear equations have?
Answer: C
When three planes intersect along a line, every point on that line is a common solution, resulting in infinitely many solutions.