1. Find [latex]{lt}_{(x,y,z)→(0,0,0)}[/latex] [latex]\frac{sin(x).sin(y)}{x.z}[/latex]
A. ∞
B. 5
C.1
D. Does Not Exist
Answer: Option D
Exaplanation:
Put x = t : y = at : z = t
= [latex]{lt}_{t→0}[/latex][latex]\frac{sin(t).sin(at)}{t}^{2}[/latex]
[latex]{lt}_{t→0}[/latex] [latex]\frac{sin(t)}{t}[/latex] x (a) x [latex]{lt}_{t→0}[/latex] [latex]\frac{sin(at)}{at}[/latex]
= (1) * (a) * (1) = a
2. Find [latex]{lt}_{(x,y,z)→(2,2,4)}[/latex] [latex]\frac{{x}^{2} + {y}^{2} - {z}^{2} + 2xy}{x + y - z}[/latex]
Answer: Option D
Exaplanation:
Simplifying the expression yields
[latex]{lt}_{(x,y,z)→(0,0,0)}[/latex] [latex]\frac{{x + y}^{2} - {z}^{2}}{(x + y)−z}[/latex]
[latex]{lt}_{(x,y,z)→(0,0,0)}[/latex] [latex]\frac{(x + y + z).(x + y − z)}{x + y − z}[/latex]
[latex]{lt}_{(x,y,z)→(0,0,0)}[/latex] (x+y+z) = 2 + 2 + 4
= 8
3. Find [latex]{lt}_{(x,y,z,w)→(3,1,1,11)}[/latex] [latex]\frac{{x}^{4} + {y}^{2} + {z}^{2} + 2{x}^{2}y + 2yz + 2{x}^{2}z - {w}^{2}} {{x}^{2} + y + z - w}[/latex]
Answer: Option D
Exaplanation:
Simplifying the expression we have
[latex]{lt}_{(x,y,z,w)→(3,1,1,11)}[/latex] [latex]\frac{{x}^{2} + y+ {z}^{2} - {w}^{2} }{{x}^{2} + y + z - w}[/latex]
[latex]{lt}_{(x,y,z,w)→(3,1,1,11)}[/latex] [latex]\frac{({x}^{2} + y+ z - w) .({x}^{2} + y+ z - w) }{{x}^{2} + y + z - w}[/latex]
[latex]{lt}_{(x,y,z,w)→(3,1,1,11)}[/latex][latex]({x}^{2} + y+ z + w)[/latex] = (32+1+1+11)
= 9+1+1+11=22
4. Given that limit exist find [latex]{lt}_{(x,y,z)→(-9,-9,-9)}[/latex] [latex]\frac{tan((x+9)(y+11)(z+7))}{(x+9)(y+10)}[/latex]
Answer: Option C
Exaplanation:
We can parameterize the curve by
x = y = z = t
[latex]{lt}_{(t)→(-9)}[/latex][latex]\frac{tan((t + 9)(t + 11)(t + 7))}{(t + 9)(t + 10)}[/latex]
[latex]{lt}_{(t)→(-9)}[/latex][latex]\frac{tan((t + 9)(t + 11)(t + 7))}{(t + 9)(t + 11)(t + 7)}[/latex] x [latex]{lt}_{(t)→(-9)}[/latex][latex]\frac{tan((t + 11)(t + 7))}{(t + 10)}[/latex]
= [latex]\frac{(−9+11)(−9+7)}{(−9+10)}[/latex] = [latex]\frac{(2)(2)}{(1)}[/latex]
= 4
5.Given that limit exist find [latex]{lt}_{(x,y,z)→(0,0,0,)}[/latex][latex]\frac{(Cos(\frac{x }{2} - x) tan(y).cot( \frac{x }{2}) - z)}{sin(x). sin(y). sin(z)}[/latex]
Answer: Option C
Exaplanation:
Put x = y = z = t
[latex]{lt}_{(x,y,z)→(0)}[/latex][latex]\frac{(Cos(\frac{x }{2} - t) tan(y).cot( \frac{x }{2}) - t)}{sin(x). sin(y). sin(z)}[/latex]
[latex]{lt}_{(x,y,z)→(0)}[/latex] [latex]\frac{(sin(t)) ({tan}^{2}(t))}{{sin}^{3}(t)}[/latex]
[latex]{lt}_{(x,y,z)→(0)}[/latex] [latex]\frac{{tan}^{2}(t)}{sin(t)}[/latex] = [latex]{lt}_{(x,y,z)→(0)} [/latex] [latex]\frac{1}{{cos}^{2}(t)}[/latex]
= [latex]\frac{1}{{cos}^{2}(t)}[/latex] = [latex]\frac{1}{1}[/latex] = 1