TOPIC: ALGEBRAIC EQUATIONS
DIRECTION: Choose the correct answer from the lettered options.
1. Factorise x2 – 4x – 21.
A. (x – 3)(x + 7).
B. (x – 7)(x + 3).
C. (x + 7)(x + 3).
D. (x – 7)(x – 3).
The correct answer is option [B]. Solution: x2 – 4x – 21; x2 – 7x + 3x – 21; x(x – 7) + 3(x – 7); (x – 7)(x + 3).
2. If
,
are the roots of the equation 3×2 = x + 1, state the value of
+
and
.
A.
11, 3 3
B.
1 1 , 3 3
C.
1 1 , 3 3
D.
1 1 , 3 3
The correct answer is option [D]. Solution: 3×2 = x + 1; 3×2 – x – 1 = 0; The sum of roots
+
= – b/a = -[-1/3] = 1/3; The product of roots,
= c/a = -1/3. Answer is 1/3, -1/3.
3. Solve the quadratic equation 2×2 – 3x – 5 = 0.
A. 1,5 2
. B. -1,2 5
. C. -1,5 2
. D. 1,52
. The correct answer is option [C]. Solution: 2×2 – 3x – 5 = 0; 2×2 + 2x – 5x – 5 = 0; 2x(x + 1) – 5(x + 1) = 0; (x + 1)(2x – 5) = 0; x = -1 or
5 2.
4. If a, b are the roots of 2×2 + x – 3 = 0, constant equation whose root is 5a, 5b.
A. 4×2 + 160x + 375.
B. 4×2 – 160x + 375.
C. 4×2 – 160x – 375.
D. 4×2 + 160x – 375.
The correct answer is option [A]. Solution: The sum of roots = 5
+ 5
; The product of root = 5
.5
; Note:
+
= -b/a = -1/2,
.
= c/a = -3/2; 5[
+
] = 5
-1/2; 25
= -75/2; [x – (-5/2)][x – (-75/2)]; (2x + 5)(2x + 75); 4×2 + 160x + 375.
5. Complete the square for the quadratic trinomial x2 + 4x + 1.
A. (x + 2)2 – 3.
B.(x +2)2 + 5.
C. (x + 2)2 + 3.
D. (x + 2)2 – 5.
The correct answer is option [A]. Solution: x2 + 4x + 1; (x2 + 4x) + 1; half the coefficient of x and subtract the square of the coefficient of x from the constant; (x + 2)2 – 4 + 1 = (x + 2)2 – 3.
6. Construct and simplify the equation whose root is -5, -6.
A. x2 – 11x – 30.
B. x2 + 11x + 30.
C. x2 + 11x – 30.
D. x2 – 11x + 30.
The correct answer is option [B]. Solution: [x – (-5)][x – (-6)]; (x + 5)(x + 6); x2 + 5x + 6x + 30; x2 + 11x + 30.
TOPIC: CIRCULAR MEASURE AND RADIANS
DIRECTION: Choose the correct answer from the lettered options.
1. Simplify, sec
– sin
tan
. A. cot
B. cosec
C. cos
D. sin
The correct answer is option [C]. Solution: sec
– sin
tan
= 1/cos
– sin
sin
/cos
= 1 – sin2
/cos
; Recall: cos2
= 1 – sin2
; cos2
/cos
= cos
.
2. Express 120o in radians as a multiple of
A. 3 /2.
B. 3/2
C. 2/3
D. 2 /3.
The correct answer is option [D].
3. Find q in the range 0o to 90o of the equation 3sin2 q = cos2 q.
A. 30o.
B. 60o.
C. 60o, 30o
D. 45o.
The correct answer is option [C].
Solution: 3sin2
= cos2
Recall: sin2
= 1 – cos2
; 3(1 – cos2
) = cos2
; 3 – 3cos2
= cos2
; cos2
= 3/4;
= cos-1
(3/4) = cos-1
3/2 = 60o; 90o – 60o = 30o.
7. An arc subtends an angle of 150o at the centre of a circle of radius 12cm. Find the length of the arc.
A. 10cm.
B. 62.8cm.
C. 15.7cm.
D. 31.4cm.
The correct answer is option [D]. Solution: Length of arc = r
, where r = 12cm,
= 150
/180 = 5
/6; Length of arc = 12
5
/6 = 10
= 31.4cm.
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