Further Mathematics 2022 Objective — Question 1
A binary operation Δ is defined on the set of real numbers R, by x Δ y = √(x+y−xy/4), where x,y∈R. Find the value of 4Δ3.
- A. 16
- B. 8
- C. 4
- D. 2Correct
Explanation
4Δ3 = √(4+3−4(3)/4) = √(7−3) = √4 = 2.
All 40 questions from the West African Examinations Council (WAEC) Further Mathematics 2022 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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A binary operation Δ is defined on the set of real numbers R, by x Δ y = √(x+y−xy/4), where x,y∈R. Find the value of 4Δ3.
4Δ3 = √(4+3−4(3)/4) = √(7−3) = √4 = 2.
Simplify [ (3√6+√54) / √5(3√5) ]⁻¹.
√54=3√6, so the numerator becomes 3√6+3√6=6√6, and the denominator √5(3√5)=15. Inverting (6√6/15)⁻¹ and rationalizing gives 5√6/12.
If log₁₀⁷⁷⁷⁽³ˣ⁻¹⁾ + log₁₀⁷⁷⁷⁴ = log₁₀⁷⁷⁷⁽⁹ˣ⁺²⁾ (i.e. log₁₀[10^(3x−1)] + log₁₀[4] = log₁₀[10^(9x+2)]), find x.
Combining the logs: log₁₀[4×10^(3x−1)] = log₁₀[10^(9x+2)], so 4(3x−1)=9x+2, giving 12x−4=9x+2, so 3x=6, x=2.
Simplify (9×3ⁿ⁺¹ − 3ⁿ⁺²) / (3ⁿ⁺¹ − 3ⁿ).
Factoring 3ⁿ out of numerator and denominator and simplifying the powers of 3 gives a result of 9.
Consider the statements: x: All wrestlers are strong. y: Some wrestlers are not weightlifters. Which of the following is a valid conclusion?
Since some wrestlers (who are all strong) are not weightlifters, it is valid to conclude that some strong wrestlers are not weightlifters. This does not make an absolute claim about all wrestlers or all weightlifters, only acknowledging a possible overlap.
The functions f:x→5x²+7x−6 and g:x→2x²+3x−7 are defined on the set of real numbers, R. Find the values of x for which 3f(x)=g(x).
3f(x)=g(x) gives 3(2x²+3x−7)... actually 3(5x²+7x−6)... solving 6x²+9x−21=5x²+7x−6 leads to x²+2x−15=0, i.e. (x−3)(x+5)=0, so x=3 or x=−5.
Express 4π/5 radians in degrees.
Using π radians = 180°: (4π/5) × (180/π) = 4×180/5 = 144°.
Given that (8x+m)/(x²−3x−4) = 5/(x+1) + 3/(x−4), find the value of m.
Combining the right side over a common denominator: [5(x−4)+3(x+1)]/[(x+1)(x−4)] = (8x−17)/[(x+1)(x−4)]. Comparing numerators, m = −17.
If x²+y²−2x−6y+5=0, evaluate dy/dx when x=3 and y=2.
Differentiating implicitly: 2x+2y(dy/dx)−2−6(dy/dx)=0, so dy/dx=(2−2x)/(2y−6). At x=3,y=2: dy/dx=(2−6)/(4−6)=(−4)/(−2)=2.
Evaluate ∫₀¹ x²(x³+2)³ dx.
Let u=x³+2, du=3x²dx. The integral becomes ∫u³/3 du = [u⁴/12], evaluated from x=0 to 1: [(1+2)⁴−(0+2)⁴]/12 = (81−16)/12 = 65/12.
If (2 −3; 1 4)(−6; k) = (3; −26), find the value of k.
From the first row: 2(−6)−3k=3, giving −12−3k=3, so k=−5 (this also satisfies the second row: −6+4(−5)=−26).
A linear transformation T is defined by T:(x,y)→(3x−y, x+4y). Find the image of (2,−1) under T.
T(2,−1) = (3(2)−(−1), 2+4(−1)) = (6+1, 2−4) = (7,−2).
Evaluate ⁴P₂ + ⁴C₂ − ⁴P₃.
⁴P₂=12, ⁴C₂=6, ⁴P₃=24. So 12+6−24 = −6.
Find the coefficient of x² in the binomial expansion of (x+2/x²)⁵.
The general term is ⁵C_r x^(5−3r)2^r. For the power of x to equal 2, 5−3r=2, so r=1. The coefficient is ⁵C₁×2¹ = 5×2 = 10.
Given that P={x: x is a multiple of 5}, Q={x: x is a multiple of 3} and R={x: x is an odd number} are subsets of μ={x: 20≤x<35}, find (P∪Q)∩R.
P={20,25,30}, Q={21,24,27,30,33}, R={21,23,25,27,29,31,33}. P∪Q={20,21,24,25,27,30,33}. Intersecting with R gives {21,25,27,33}.
A particle moving with a velocity of 5m/s accelerates at 2m/s². Find the distance it covers in 4 seconds.
Using s=ut+½at²: s=5(4)+½(2)(4²) = 20+16 = 36m.
If Uₙ=kn²+pn, U₁=−1, U₅=15, find the values of k and p.
U₁: k+p=−1. U₅: 25k+5p=15. Substituting p=−1−k into the second equation gives 20k=20, so k=1 and p=−2.
In how many ways can six persons be paired?
The number of ways to select 2 people from 6 (as one pair, ignoring order) is ⁶C₂ = 15.
Solve 3^(2x−2) − 28(3^(x−2)) + 3 = 0.
Dividing through by 3⁻² and letting y=3ˣ gives y²−28y+27=0, i.e. (y−27)(y−1)=0, so 3ˣ=27 or 3ˣ=1, giving x=3 or x=0.
Given that P=(−4,−5) and Q=(2,3), express PQ in the form (k,θ), where k is the magnitude and θ is the bearing.
PQ=Q−P=(6,8), so |PQ|=√(36+64)=10 units. The angle from the y-axis (bearing) works out to 037° (found via 90°−tan⁻¹(8/6)).
If PQ=−2i+5j and RQ=−i−7j, find PR.
QR=−RQ=i+7j. PR=PQ+QR=(−2i+5j)+(i+7j) = −i+12j.
The table shows the distribution of distance (in km) covered by 40 hunters while hunting: Distance(km) 3,4,5,6,7,8; Frequency 5,4,x,9,2x,1. If a hunter is selected at random, find the probability that the hunter covered at least 6km.
Since frequencies sum to 40: 5+4+x+9+2x+1=40, giving 3x=21, x=7. P(at least 6km) = (9+2(7)+1)/40 = 24/40 = 3/5.
Using the same distribution, find the mode of the distribution.
With x=7, the frequencies are 5,4,7,9,14,1 for distances 3–8. The highest frequency (14) corresponds to a distance of 7km, so the mode is 7.
If g(x)=√(1−x²), find the domain of g(x).
For g(x) to be defined, 1−x²≥0, i.e. (1−x)(1+x)≥0, which holds for −1≤x≤1.
Find the coefficient of x³y² in the binomial expansion of (x−2y)⁵.
The term in x³y² is ⁵C₂x³(−2y)² = 10x³(4y²) = 40x³y², so the coefficient is 40.
The first, second and third terms of an exponential sequence (G.P.) are (x−4), (x+2) and (3x+1) respectively. Find the values of x.
For a G.P., (x+2)/(x−4) = (3x+1)/(x+2). Cross-multiplying: (x+2)²=(x−4)(3x+1), which simplifies to 2x²−15x−8=0, i.e. (2x+1)(x−8)=0, so x=−1/2 or x=8.
A body of mass 18kg moving with velocity 4ms⁻¹ collides with another body of mass 6kg moving in the opposite direction with velocity 10ms⁻¹. If they stick together after collision, find their common velocity.
By conservation of momentum: 18(4)+6(−10)=(18+6)v, so 72−60=24v, giving v=12/24=½ ms⁻¹. None of the listed options equal ½ ms⁻¹ exactly — the correct computed value is 0.5ms⁻¹.
The mean heights of three groups of students consisting of 20, 16 and 14 students each are 1.67m, 1.5m and 1.40m respectively. Find the mean height of all the students.
Total height = 20(1.67)+16(1.5)+14(1.40) = 33.4+24+19.6 = 77m. Total students = 50. Mean = 77/50 = 1.54m.
Find, correct to the nearest degree, the acute angle formed by the lines y=2x+5 and 2y=x−6.
Gradients: m₁=2 and m₂=½. θ=tan⁻¹[(m₁−m₂)/(1+m₁m₂)] = tan⁻¹[(1.5)/(2)] = tan⁻¹(0.75) ≈ 37°.
Solve 4sin²θ+1=2, where 0°<θ<180°.
4sin²θ=1, so sin²θ=¼, sinθ=±½. For 0°<θ<180°, sinθ=½ gives θ=30° or θ=150°.
Find the range of values of x for which 2x²+7x−15≥0.
Factoring: 2x²+7x−15 = (2x−3)(x+5). This is ≥0 when x≤−5 or x≥3/2.
The probability that a student will graduate from a college is 0.4. If 3 students are selected from the college, what is the probability that at least one student will graduate?
P(at least one graduates) = 1−P(none graduate) = 1−(0.6)³ = 1−0.216 = 0.784 ≈ 0.78.
The equation of a circle is given as 2x²+2y²−x−3y−41=0. Find the coordinates of its centre.
Dividing through by 2: x²+y²−½x−¹⁄₂x... more precisely x²+y²−(1/2)x−(3/2)y−41/2=0. Comparing to x²+y²+2gx+2fy+c=0: g=−¼, f=−¾. The centre is (−g,−f) = (¼, ¾).
The gradient of a function at any point (x,y) is 2x−6. If the function passes through (1,2), find the function.
Integrating dy/dx=2x−6 gives y=x²−6x+c. Substituting (1,2): 2=1−6+c, so c=7. Thus y=x²−6x+7.
A particle of mass 3kg moving along a straight line under the action of a force FN, covers a line distance, d, at time, t, such that d=t²+3t. Find the magnitude of F at time t.
Velocity = dd/dt = 2t+3. Acceleration = d²d/dt² = 2 (constant). Force F=ma=3×2=6N.
If α and β are the roots of x²+mx−n=0, where m and n are constants, form the equation whose roots are 1/α and 1/β.
α+β=−m, αβ=−n. Sum of new roots = (α+β)/αβ = m/n; product of new roots = 1/αβ = −1/n. The equation x²−(sum)x+product=0 becomes x²−(m/n)x−(1/n)=0, or nx²−mx−1=0.
A particle is acted upon by forces F=(10N,060°), P=(15N,120°) and Q=(12N,200°). Express the force that will keep the particle in equilibrium in the form xi+yj, where x and y are scalars.
Resolving all three forces: ΣF(x)=10sin60+15sin60−12sin20≈17.55N, ΣF(y)=10cos60−15cos60−12cos20≈−13.78N. The resultant is 17.55i−13.78j; the equilibrant (force needed for equilibrium) is the negative of this: −17.55i+13.78j.
Evaluate lim(x→−2) (x³+8)/(x+2).
Factoring: x³+8=(x+2)(x²−2x+4). Cancelling (x+2) leaves x²−2x+4, which at x=−2 gives 4+4+4=12.
If f(x−1)=x³+3x²+4x−5, find f(2).
For f(2), set x−1=2, so x=3. f(2)=3³+3(3²)+4(3)−5 = 27+27+12−5 = 61.
The length of the line joining points (x,4) and (−x,3) is 7 units. Find the value of x.
Distance = √[(−x−x)²+(3−4)²] = 7. Squaring: 4x²+1=49, so x²=12, giving x=√12=2√3.
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