Hey bilgate, good to see you again.
Here are the solutions for the questions from the image:
Question No. 3
(i) Given the functions f:x↦2x+3 and g:x↦x−1.
So, f(x)=2x+3 and g(x)=x−1.
(a) Find f(−2)
Step 1: Substitute x=−2 into the function f(x).
f(−2)=2(−2)+3
f(−2)=−4+3
f(−2)=−1
The value of f(−2) is −1.
(b) Find g−1(x)
Step 1: Let y=g(x), so y=x−1.
Step 2: Swap x and y to find the inverse relation.
x=y−1
Step 3: Solve for y to express g−1(x).
y=x+1
The inverse function g−1(x) is x+1.
(c) Find fg(x)
Step 1: Substitute g(x) into f(x).
fg(x)=f(g(x))=f(x−1)
Step 2: Replace x in the expression for f(x) with (x−1).
fg(x)=2(x−1)+3
fg(x)=2x−2+3
fg(x)=2x+1
The composite function fg(x) is 2x+1.
(d) Find the value of x, for which f(x)=g(x)
Step 1: Set the expressions for f(x) and g(x) equal to each other.
2x+3=x−1
Step 2: Solve the equation for x.
2x−x=−1−3
x=−4
The value of x is −4.
(ii) Using only a pencil, ruler and a pair of compasses,
(a) Draw the line PQ = 6cm
Draw a straight line segment and mark two points P and Q on it such that the distance between them is 6 cm.
(b) Construct the perpendicular bisector of PQ to meet PQ at M
- Place the compass needle at P and open it to a radius greater than half the length of PQ. Draw arcs above and below the line segment PQ.
- Without changing the compass radius, place the needle at Q and draw arcs above and below PQ, intersecting the first set of arcs.
- Draw a straight line connecting the two points where the arcs intersect. This line is the perpendicular bisector of PQ.
- Mark the point where the perpendicular bisector intersects PQ as M.
(c) Draw the line PS = 5cm, where S is a point on the perpendicular bisector
- Place the compass needle at P and open it to a radius of 5 cm.
- Draw an arc that intersects the perpendicular bisector (constructed in part b).
- Mark the point of intersection on the perpendicular bisector as S.
- Draw a straight line segment connecting P and S. The length of PS will be 5 cm.
Question No. 4
(i) Given the function f(x)=x2−3x−4, for −2≤x≤5:
(a) Copy and complete the following table
Step 1: Calculate f(x) for each given value of x using the formula f(x)=x2−3x−4.
• For x=−2: f(−2)=(−2)2−3(−2)−4=4+6−4=6
• For x=−1: f(−1)=(−1)2−3(−1)−4=1+3−4=0
• For x=0: f(0)=(0)2−3(0)−4=0−0−4=−4
• For x=1: f(1)=(1)2−3(1)−4=1−3−4=−6
• For x=2: f(2)=(2)2−3(2)−4=4−6−4=−6
• For x=3: f(3)=(3)2−3(3)−4=9−9−4=−4
• For x=4: f(4)=(4)2−3(4)−4=16−12−4=0
• For x=5: f(5)=(5)2−3(5)−4=25−15−4=6
Step 2: Complete the table with the calculated values.
| x | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|
| y=f(x) | 6 | 0 | -4 | -6 | -6 | -4 | 0 | 6 |
(b) Find the minimum value of y=f(x) and the corresponding value of x
Step 1: The minimum value of a quadratic function ax2+bx+c occurs at x=−2ab.
For f(x)=x2−3x−4, we have a=1 and b=−3.
x=−2(1)−3=23=1.5
Step 2: Substitute x=1.5 into f(x) to find the minimum value.
f(1.5)=(1.5)2−3(1.5)−4
f(1.5)=2.25−4.5−4
f(1.5)=−6.25
The minimum value of y=f(x) is −6.25 at x=1.5.
(c) Solve the equation f(x)=0
Step 1: Set the function f(x) equal to 0.
x2−3x−4=0
Step 2: Factor the quadratic equation.
(x−4)(x+1)=0
Step 3: Solve for x.
x−4=0orx+1=0
x=4orx=−1
The solutions for f(x)=0 are x=−1orx=4.
(ii) Given a 2×2 matrix, P defined by P=(3k2k6), where k is a constant.
(a) Find P when k=2
Step 1: Substitute k=2 into the matrix P.
P=(322(2)6)
P=(3246)
The matrix P when k=2 is (3246).
(b) Hence or otherwise, find Adj. P, the adjoint of P.
Step 1: For a 2×2 matrix A=(acbd), its adjoint is given by Adj A=(d−c−ba).
Step 2