You're on a roll —
Step 1: Solve Question 24.
The two lines are given by:
r1=3i−j+k+λ(i+2j−k)
r2=4i+4j+k+μ(−i+j+2k)
For the lines to intersect, r1=r2.
Equating the components:
For i: 3+λ=4−μ(1)
For j: −1+2λ=4+μ(2)
For k: 1−λ=1+2μ(3)
From equation (1), λ+μ=1.
From equation (2), 2λ−μ=5.
Add these two equations:
(λ+μ)+(2λ−μ)=1+5
3λ=6
λ=2
Substitute λ=2 into λ+μ=1:
2+μ=1
μ=1−2
μ=−1
Now, check these values in equation (3):
1−λ=1+2μ
1−2=1+2(−1)
−1=1−2
−1=−1
The values λ=2 and μ=−1 satisfy all three equations, so the lines intersect.
The correct option is B.
The final answer is B.
Step 2: Solve Question 25.
We need to arrange 5 girls on a bench, with the condition that two specific left-handed girls must be together.
Treat the two left-handed girls as a single unit.
Now we have 4 "units" to arrange: (LH1 LH2), G3, G4, G5.
The number of ways to arrange these 4 units is 4!.
4!=4×3×2×1=24.
Within the unit of the two left-handed girls, they can be arranged in 2! ways (LH1 LH2 or LH2 LH1).
2!=2×1=2.
The total number of ways to arrange the 5 girls such that the two left-handed girls are together is the product of these two numbers:
Total ways = 4!×2!=24×2=48.
The correct option is B.
The final answer is B.
Step 3: Solve Question 26.
We need to simplify the expression sin(x+6π)−sin(x−6π).
Use the sum-to-product trigonometric identity:
sinA−sinB=2cos(2A+B)sin(2A−B)
Here, A=x+6π and B=x−6π.
First, find 2A+B:
2A+B=2(x+6π)+(x−6π)=22x=x
Next, find 2A−B:
2A−B=2(x+6π)−(x−6π)=2x+6π−x+6π=262π=23π=6π
Substitute these into the identity:
sin(x+6π)−sin(x−6π)=2cos(x)sin(6π)
We know that sin(6π)=sin(30∘)=21.
So, the expression becomes:
2cos(x)(21)=cos(x)
The correct option is C.
The final answer is C.
Step 4: Solve Question 27.
The given function is y=x2−14.
To find vertical asymptotes, set the denominator equal to zero:
x2−1=0
(x−1)(x+1)=0
x=1 or x=−1
So, there are two vertical asymptotes at x=±1.
To find horizontal asymptotes, consider the limit as x→±∞:
limx→±∞x2−14
As x→±∞, x2−1→∞.
So, limx→±∞x2−14=0.
Thus, there is a horizontal asymptote at y=0.
The graph has two vertical asymptotes at x=±1 and a horizontal asymptote at y=0.
The correct option is D.
The final answer is D.
Step 5: Solve Question 28.
Given the differential equation dxdy−2xy=0.
We can rewrite this as dxdy=2xy.
This is a separable differential equation.
ydy=2xdx
Integrate both sides:
∫y1dy=∫2xdx
ln∣y∣=x2+C
Exponentiate both sides:
∣y∣=ex2+C
y=±eCex2
Let A=±eC, where A is an arbitrary non-zero constant.
y=Aex2
We are given the initial condition y=1 when x=1.
Substitute these values into the general solution:
1=Ae(1)2
1=Ae1
A=e1=e−1
Substitute the value of A back into the general solution:
y=e−1ex2
y=ex2−1
The correct option is A.
The final answer is A.
Step 6: Solve Question 29.
We need to find the coefficient of x2 in the binomial expansion of (1+21x)5.
The binomial theorem states that the general term in the expansion of (a+b)n is given by Tr+1=(rn)an−rbr.
In this case, a=1, b=21x, and n=5.
We want the term with x2, so we set r=2.
T2+1=T3=(25)(1)5−2(21x)2
T3=(25)(1)3(21)2(x)2
Calculate (25):
(25)=2!(5−2)!5!=2!3!5!=2×15×4=10
Substitute this value back:
T3=10×1×41×x2
T3=410x2
T3=25x2
The coefficient of x2 is 25.
Wait, let me recheck the options. The options are 321, −161, 161, −321. My calculated coefficient 25 is not among the options.
Let me re-read the question carefully. It says (1+21x)5.
My calculation is correct for this expression.
Let me check if the image is clear. The exponent is definitely 5.
Perhaps the question intended a different exponent or a different term.
Let me assume there might be a typo in the question or options.
If the question was (1+21x)−5, then the general term for (1+y)n is ∑r=0∞(rn)yr.
For n=−5 and y=21x, the coefficient of x2 would be (2−5)(21)2.
(2−5)=2!(−5)(−5−1)=2(−5)(−6)=230=15.
So, 15×41=415. Still not matching.
What if the expression was (1+x)21? No, it's (1+21x)5.
Let me re-evaluate the calculation for (25).
(25)=2×15×4=10. This is correct.
(21x)2=41x2. This is correct.
Coefficient is 10×41=410=25. This is correct.
Given the options, there might be a misunderstanding of the question or a typo in the question/options.
Let's consider if the question was (1+2x1)5. No, it's clearly 21x.
What if the exponent was different?
If the exponent was, for example, −2, then (2−2)(21)2=2(−2)(−3)×41=3×41=43.
If the exponent was −1, then (2−1)(21)2=2(−1)(−2)×41=1×41=41.
Let's re-examine the image for the exponent. It looks like a 5.
Let's assume there's a typo in the question and it was meant to be (1+21x)−2 or something similar that would lead to one of the options.
However, I must solve the question as written.
My calculated answer is 25. Since this is not among the options, I will state my calculated answer and note the discrepancy.
Let me check if I misread the options.
A: 321
B: −161
C: 161
D: −321
None of these match 25.
I will proceed with the calculation as it is, and state the result.
The coefficient of x2 is 25.
Since 25 is not among the options, there might be an error in the question or the provided options.
I will select the closest option if forced, but that's not ideal.
Let me re-read the question one more time. "The coefficient of x2 in the binomial expansion of (1+21x)5 is".
The calculation is straightforward and seems correct.
Let's consider if the question was (1+2x1)5. No, it's clearly 21x.
What if the question was (1+x)21?
Then the expansion is 1+21x+2!21(21−1)x2+⋯=1+21x+221(−21)x2+⋯=1+21x−81x2+….
The coefficient of x2 would be −81. Still not matching.
What if the question was (1+x)−2?
Then the expansion is 1+(−2)x+2!(−2)(−3)x2+⋯=1−2x+3x2+….
The coefficient of x2 would be 3. Still not matching.
What if the question was (1+21x)−1?
Then the expansion is 1+(−1)(21x)+2!(−1)(−2)(21x)2+⋯=1−21x+1⋅41x2+⋯=1−21x+41x2+….
The coefficient of x2 would be 41. Still not matching.
What if the question was (1+21x)−4?
Then the coefficient of x2 would be (2−4)(21)2=2(−4)(−5)×41=10×41=25. This is the same as my original answer.
Let's consider the possibility that the question is (1+x)n and the coefficient of x2 is one of the options.
If the coefficient of x2 is 161, then (2n)(21)2=161.
2n(n−1)×41=161
8n(n−1)=161
n(n−1)=168=21.
2n2−2n−1=0. This does not give an integer n.
Let's assume the question is correct as written and my calculation is correct.
The coefficient of x2 in the binomial expansion of (1+21x)5 is 25.
Since this is not an option, I will state the calculated value.
The final answer is 25.
(Note: This answer is not among the provided options, which suggests a potential error in the question or options.)
Step 7: Solve Question 30.
We need to find the coordinates of the points where the curves y=2x−3 and y=x2−2x intersect.
Set the two expressions for y equal to each other:
2x−3=x2−2x
Rearrange the equation to form a quadratic equation:
0=x2−2x−2x+3
0=x2−4x+3
Factor the quadratic equation:
We need two numbers that multiply to 3 and add to -4. These are -1 and -3.
(x−1)(x−3)=0
So, x=1 or x=3.
Now, find the corresponding y values using y=2x−3:
For $x=1