Question 1. Limx→0[sin3x/5x]
Solution:
We have,
Limx→0[sin3x/5x]
= (1/5)Limx→0[sin3x/3x] × 3
= (3/5)Limx→0[sin3x/3x]
As we know that, Limx→0[sinx/x] = 1
= (3/5)
Question 2. Limx→0[sinx°/x]
Solution:
We have,
Limx→0[sinx°/x]
As we know that x° = [(πx)/180]
= Limx→0[sin{(πx)/180}/x]
=
\lim_{x\to0}\frac{sin\frac{πx}{180}}{\frac{πx}{180}}×\frac{π}{180} = (π/180) × 1
= (π/180)
Question 3. Limx→0[x2/sinx2]
Solution:
We have,
Limx→0[x2/sinx2]
=
Lim_{x→0}[\frac{1}{\frac{sinx^2}{x^2}}] =
[\frac{1}{ Lim_{x→0}\frac{sinx^2}{x^2}}] As we know that, Limx→0[sinx/x] = 1
= 1/1
= 1
Question 4. Limx→0[sinx.cosx/3x]
Solution:
We have,
Limx→0[(sinx.cosx)/3x]
= Limx→0[(sinx.cosx)/ × 3x]
= 1/3 Limx→0[(sinx)/x] × Limx→0[(cosx)]
As we know that Limx→0[sinx/x] = 1, and Limx→0cos0 = 1
= (1/3) × 1 × 1
= 1/3
Question 5. Limx→0[(3sinx - 4sin3x)/x]
Solution:
We have,
Limx→0[(3sinx - 4sin3x)/x]
As we know that 3sinx - 4sin3x = sin3x
= Limx→0[(sin3x)/3x] × 3
= 3 × Limx→0[(sin3x)/3x]
As we know that, Limx→0[sinx/x] = 1
= 3 × 1
= 3
Question 6. Limx→0[tan8x/sin2x]
Solution:
We have,
Limx→0[tan8x/sin2x]
=
\lim_{x\to0}[\frac{tan8x}{8x}×8x][\frac{1}{\frac{sin2x}{2x}×2x}] =
\lim_{x\to0}[\frac{tan8x}{8x}][\frac{1}{\frac{sin2x}{2x}}]×\frac{8x}{2x} As we know that Limx→0[sin2x/2x] = 1 and Limx→0[tan8x/8x] = 1
= 8/2
= 4
Question 7. Limx→0[tan(mx)/tan(nx)]
Solution:
We have,
Limx→0[tan(mx)/tan(nx)]
=
\lim_{x\to0}[\frac{tanmx}{mx}×mx][\frac{1}{\frac{tannx}{nx}×nx}] =
\lim_{x\to0}[\frac{tanmx}{mx}][\frac{1}{\frac{tannx}{nx}}]×\frac{mx}{nx} As we know that Limx→0[tanx/x] = 1
= m × 1/n × 1
= m/n
Question 8. Limx→0[sin5x/tan3x]
Solution:
We have,
Limx→0[sin5x/tan3x]
=
\lim_{x\to0}[\frac{sin5x}{5x}×5x][\frac{1}{\frac{tan3x}{3x}×3x}] =
\lim_{x\to0}[\frac{sin5x}{5x}][\frac{1}{\frac{tan3x}{3x}}]×\frac{5x}{3x} As we know that Limx→0[sin5x/5x] = 1 and Limx→0[tan3x/3x] = 1
= 5/3 × 1
= 5/3
Question 9. Limx→0[sin(xn)/(xn)]
Solution:
We have,
Limx→0[sin(xn)/(xn)]
It is in the form of 0/0
So, let xn = y
x→0 than y→0
Limy→0[siny/y]
As we know that Limy→0[siny/y] = 1
= 1
Question 10. Limx→0[(7xcosx - 3sinx)/(4x + tanx)]
Solution:
We have,
Limx→0[(7xcosx - 3sinx)/(4x + tanx)]
= Limx→0[x(7cosx-3sinx/x)/x(4 + tanx/x)]
= Limx→0[(7cosx-3sinx/x)/(4 + tanx/x)]
=
\frac{7\lim_{x\to0}cosx-3\lim_{x\to0}\frac{sinx}{x}}{4+\lim_{x\to0}\frac{tanx}{x}} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (7 - 3)/(4 + 1)
= 4/5
Question 11. Limx→0[{cos(ax) - cos(bx)}/{cos(cx) - cos(dx)}]
Solution:
We have,
Limx→0[{cos(ax) - cos(bx)}/{cos(cx) - cos(dx)}]
=
\lim_{x\to0}[\frac{-2sin(\frac{ax+bx}{2})sin(\frac{ax-bx}{2})}{-2sin(\frac{cx+dx}{2})sin(\frac{cx-dx}{2})}] =
\lim_{x\to0}[\frac{\frac{sin(\frac{ax+bx}{2})}{(\frac{ax+bx}{2})}×(\frac{ax+bx}{2})\frac{sin(\frac{ax-bx}{2})}{(\frac{ax-bx}{2})}×(\frac{ax-bx}{2})}{\frac{sin(\frac{cx+dx}{2})}{(\frac{cx+dx}{2})}×(\frac{cx+dx}{2})\frac{sin(\frac{cx-dx}{2})}{(\frac{cx-dx}{2})}×(\frac{cx-dx}{2})}] =
\lim_{x\to0}[\frac{\frac{(ax+bx)}{2}\frac{(ax-bx)}{2}}{\frac{(cx+dx)}{2}\frac{(cx-dx)}{2}}] =
\lim_{x\to0}[\frac{x^2(a+b)(a-b)}{x^2(c+d)(c-d)}] = (a2 - b2)/(c2 - d2)
Question 12. Limx→0[(tan23x)/x2]
Solution:
We have,
Limx→0[(tan23x)/x2]
= Limx→0[(tan3x)/x]2
= Limx→0[(tan3x)/3x]2 × 9
As we know that Limx→0[tanx/x] = 1
= 1 × 9
= 9
Question 13. Limx→0[(1 - cosmx)/x2]
Solution:
We have,
Limx→0[(1 - cosmx)/x2]
=
\lim_{x\to0}[\frac{2sin^2\frac{mx}{2}}{x^2}] =
2\lim_{x\to0}[\frac{sin\frac{mx}{2}}{x}]^2 =
2\lim_{x\to0}[\frac{sin\frac{mx}{2}}{\frac{mx}{2}}]^2×(\frac{m}{2})^2 As we know that Limx→0[sinx/x] = 1
= 2 × (m/2)2
= m2/2
Question 14. Limx→0[(3sin2x + 2x)/(3x + 2tan3x)]
Solution:
We have,
Limx→0[(3sin2x + 2x)/(3x + 2tan3x)]
= Limx→0[2x(1 + 3sin2x/2x)/3 x (1 + 2tan3x/3x)]
= (2/3)Limx→0[(1 + 3sin2x/2x)/3 x (1 + 2tan3x/3x)]
=
\frac{2}{3}\lim_{x\to0}\frac{1+3\lim_{x\to0}\frac{sin2x}{2x}}{1+2\lim_{x\to0}\frac{tan3x}{3x}} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (2/3) × (4/3)
= 8/9
Question 15. Limx→0[(cos3x - cos7x)/x2]
Solution:
We have,
=
\lim_{x\to0}[\frac{-2sin(\frac{3x+7x}{2})sin(\frac{3x-7x}{2})}{x^2}] = Limx→0[-2sin5x.sin(-2x)/x2]
= Limx→0[2sin5x.sin2x/x2]
=
2\lim_{x\to0}[\frac{sin5x}{5x}×5]×\lim_{x\to0}[\frac{sin2x}{2x}×2] As we know that Limx→0[sinx/x] = 1
= 2 × 5 × 2
= 20
Question 16. Limθ→0[sin3θ/tan2θ]
Solution:
We have,
Limθ→0[sin3θ/tan2θ]
=
\lim_{θ\to0}[\frac{sin3θ}{3θ}×3θ][\frac{1}{\frac{tan2θ}{2θ}×2θ}] =
\lim_{x\to0}[\frac{sin3θ}{3θ}][\frac{1}{\frac{tan2θ}{2θ}}]×\frac{3θ}{2θ} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= 3/2
Question 17. Limx→0[sinx2(1 - cosx2)/x6]
Solution:
We have,
Limx→0[sinx2(1 - cosx2)/x6]
= Limx→0[sinx2{2sin(x2/2}/x6]
=
2\lim_{x\to0}[\frac{sinx^2.sin^2(\frac{x^2}{2})}{x^6}] =
2\lim_{x\to0}(\frac{sinx^2}{x^2})(\frac{sin\frac{x^2}{2}}{\frac{x^2}{2}×2})^2 =
2\lim_{x\to0}(\frac{sinx^2}{x^2})(\frac{sin\frac{x^2}{2}}{\frac{x^2}{2}})^2×\frac{1}{4} As we know that Limx→0[sinx/x] = 1
= 2 × (1/4)
= 1/2
Question 18. Limx→0[sin2(4x2)/x4]
Solution:
We have,
Limx→0[sin2(4x2)/x4]
= Limx→0[(sin(4x2))2/(x2)2]
= Limx→0[sin(4x2)/4x2]2 × 42
As we know that Limx→0[sinx/x] = 1
= 42
= 16
Question 19. Limx→0[(xcosx + 2sinx)/(x2 + tanx)]
Solution:
We have,
Limx→0[(xcosx + 2sinx)/(x2 + tanx)]
= Limx→0[x(cosx + 2sinx/x)/x(x + tanx/x)]
= Limx→0[(cosx + 2sinx/x)/(x + tanx/x)]
=
\frac{\lim_{x\to0}cosx+2\lim_{x\to0}\frac{sinx}{x}}{\lim_{x\to0}x+\lim_{x\to0}\frac{tanx}{x}} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (1 + 2)/(0 + 1)
= 3
Question 20. Limx→0[(2x - sinx)/(x + tanx)]
Solution:
We have,
Limx→0[(2x - sinx)/(x + tanx)]
= Limx→0[x(2 - sinx/x)/x(1 + tanx/x)]
= Limx→0[(2 - sinx/x)/(1 + tanx/x)]
=
\frac{2-\lim_{x\to0}\frac{sinx}{x}}{1+\lim_{x\to0}\frac{tanx}{x}} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (2 - 1)/(1 + 1)
= 1/2
Question 21. Limx→0[(5xcosx + 3sinx)/(3x2 + tanx)]
Solution:
We have,
Limx→0[(5xcosx + 3sinx)/(3x2 + tanx)]
= Limx→0[x(5cosx + 3sinx/x)/x(3x + tanx/x)]
= Limx→0[(5cosx + 3sinx/x)/(3x + tanx/x)]
=
\frac{5\lim_{x\to0}cosx+3\lim_{x\to0}\frac{sinx}{x}}{3\lim_{x\to0}x+\lim_{x\to0}\frac{tanx}{x}} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (5 cos0 + 3)/(0 + 1)
= 8
Question 22. Limx→0[(sin3x - sinx)/(sinx)]
Solution:
We have,
Limx→0[(sin3x - sinx)/(sinx)]
=
\lim_{x\to0}[\frac{2cos(\frac{3x+x}{2})sin(\frac{3x-x}{2})}{sinx}] = 2Limx→0[cos2x.sinx/sinx]
= 2Limx→0cos2x
= 2 × cos0
= 2 × 1
= 2
Question 23. Limx→0[(sin5x - sin3x)/(sinx)]
Solution:
We have,
Limx→0[(sin5x - sin3x)/(sinx)]
=
\lim_{x\to0}[\frac{2cos(\frac{5x+3x}{2})sin(\frac{5x-3x}{2})}{sinx}] = 2Limx→0[cos4x.sinx/sinx]
= 2Limx→0cos4x
= 2 × cos0
= 2 × 1
= 2
Question 24. Limx→0[(cos3x - cos5x)/x2]
Solution:
We have,
Limx→0[(cos3x - cos5x)/x2]
=
\lim_{x\to0}[\frac{-2sin(\frac{3x+5x}{2})sin(\frac{3x-5x}{2})}{x^2}] = Limx→0[-2sin4x.sin(-x)/x2]
= Limx→0[2sin4x.sinx/x2]
=
2\lim_{x\to0}[\frac{sin4x}{4x}×4]×\lim_{x\to0}[\frac{sinx}{x}] As we know that Limx→0[sinx/x] = 1
= 2 × 4 × 1
= 8
Question 25. Limx→0[(tan3x - 3x)/(3x - sin2x)]
Solution:
We have,
Limx→0[(tan3x - 3x)/(3x - sin2x)]
= Limx→0[x(tan3x/x - 3)/x(3 - sin2x/x)]
= Limx→0[(tan3x/x - 3)/(3 - sin2x/x)]
=
\lim_{x\to0}[\frac{\frac{tan3x}{3x}×3-2}{3-\frac{sinx}{x}×sinx}] As we know that Limx→0[sinx/x] = 1
= (3 - 2)/(3 - 0)
= 1/3
Question 26. Limx→0[{sin(2 + x) - sin(2 - x)}/x]
Solution:
We have,
Limx→0[{sin(2 + x) - sin(2 - x)}/x]
=
\lim_{x\to0}[\frac{2cos(\frac{2+x+2-x}{2})sin(\frac{2+x-2+x}{2})}{x}] = 2Limx→0[cos2.sinx/x]
= 2cos×2Limx→0[sinx/x]
As we know that Limx→0[sinx/x] = 1
= 2cos2
Question 27. Limh→0[{(a + h)2sin(a + h) - a2sina}/h]
Solution:
We have,
Limh→0[{(a + h)2sin(a + h) - a2sina}/h]
= Limh→0[{a2sin(a + h) + h2sin(a + h) + 2ahsin(a + h) - a2sina}/h]
=
\lim_{h\to0}[a^2(\frac{sin(a+h)-sina}{h}+\frac{h^2sin(a+h)}{h}+\frac{2ahsin(a+h)}{h}] =
\lim_{h\to0}[a^2\frac{2cos\frac{(a+h+a)}{2}sin\frac{(a+h-a)}{2}}{2×\frac{h}{2}}+hsin(a+h)+2asin(a+h)] =
\lim_{h\to0}[a^2cos(\frac{a+h+a}{2})+hsin(a+h)+2asin(a+h) = a2cosa + 0 + 2asina
= a2cosa + 2asina
Question 28. Limx→0[{tanx - sinx}/{sin3x - 3sinx}]
Solution:
We have,
Limx→0[{tanx - sinx}/{sin3x - 3sinx}]
=
\lim_{x\to0}[\frac{\frac{sinx}{cosx}-sinx}{3sinx-4sin^3x-3sinx}] =
\frac{-1}{4}\lim_{x\to0}[\frac{sinx(\frac{1}{cosx}-1)}{sin^2x.sinx}] =
\frac{-1}{4}\lim_{x\to0}[\frac{(\frac{1-cosx}{cosx})}{1-cos^2x}] =
\frac{-1}{4}\lim_{x\to0}[\frac{(1-cosx)}{cosx(1-cosx)(1+cosx)}] =
\frac{-1}{4}\lim_{x\to0}[\frac{1}{cosx(1+cosx)}] = (-1/4)(1/2)
= -(1/8)
Question 29. Limx→0[{sex5x - sec5x}/{sec3x - secx}]
Solution:
We have,
Limx→0[{sex5x - sec5x}/{sec3x - secx}]
=
\lim_{x\to0}\frac{\frac{1}{cos5x}-\frac{1}{cos3x}}{\frac{1}{cos3x}-\frac{1}{cosx}} =
\lim_{x\to0}(\frac{cos3x-cos5x}{cosx-cos3x})(\frac{cosx.cos3x}{cos3x.cos5x}) =
\lim_{x\to0}[\frac{-2sin4x.sin(-x)}{-2sin2x.sin(-x)}][\frac{cosx}{cos5x}] =
\lim_{x\to0}[\frac{sin4x}{sin2x}][\frac{cosx}{cos5x}] =
\lim_{x\to0}[\frac{\frac{sin4x}{4x}×4x}{\frac{sin2x}{2x}×2x}][\frac{cosx}{cos5x}] As we know that Limx→0[sinx/x] = 1
= (4x/2x)(cos0/cos0)
= 2
Question 30. Limx→0[{1 - cos2x}/{cos2x - cos3x}]
Solution:
We have,
Limx→0[{1 - cos2x}/{cos2x - cos3x}]
=
\lim_{x\to0}[\frac{2sin^2x}{-2sin(\frac{3x+7x}{2})sin(\frac{3x-7x}{2})}] =
\lim_{x\to0}[\frac{2sin^2x}{2sin(5x)sin(3x)}] =
\lim_{x\to0}[\frac{sinx.sinx}{sin(5x)sin(3x)}] =
\lim_{x\to0}[\frac{(\frac{sinx}{x}×x)(\frac{sinx}{x}×x)}{(\frac{sin5x}{5x}×5x)(\frac{sin3x}{3x}×3x)} As we know that Limx→0[sinx/x] = 1
= (1/5 × 3)
= 1/15
Question 31. Limx→0[(1 - cos2x + tan2x)/(xsinx)]
Solution:
We have,
Limx→0[(1 - cos2x + tan2x)/(xsinx)]
= Limx→0[(2sin2x + tan2x)/(xsinx)]
Dividing numerator and denominator by x2
=
\lim_{x\to0}\frac{2(\frac{sinx}{x})^2 \times x^2+(\frac{tanx}{x})^2\times x^2}{\lim_{x\to0}(\frac{sinx}{x})\times x^2} As we know that Limx→0[sinx/x] = 1 and Limx→0[tanx/x] = 1
= (2 × 1 × x2 + 1) + (1 × x2) /(1 × x2)
= 3