Differentiation Silly Question

IIT JEE Guidance › Calculus questions › Differentiation Silly Question

Let x={a₁,a₂,a₃,......,a₆} and y={b₁,b₂,b₃}. Then number of functions f from x to y such that it is onto and there are exactly three elements in x such that f(x) =b₁, is
a) 75 b) 90
c) 100 d) 120

Ans: (d)

Please explain how to get answer?
I am not getting by formula.

#Mathematics #Calculus

UP 0 DOWN 0 0 2
Post on FacebookPost anonymously?

2 Answers

262

Aditya Bhutra ·2012-04-02 12:06:31

ways of choosing 3 elements of set x ( for f(x) =b1) = ⁶C₃ = 20

now we are left with x={A,B,C} and y={M,N}

number of onto functions in this case = 2*³C₂*1 = 6

thus total number of functions = 20*6 =120

UP 0 DOWN 0
Post on FacebookPost anonymously?

Athenes Analyst ·2012-04-02 14:00:44

Thanks Aditya...I got this.. :)

UP 0 DOWN 0
Post on FacebookPost anonymously?

Your Answer

Basic Integral Calculus Operators Symbols Matrix Cases

√ √ || {} [] () → ~ ^ x x x → → ln log lg lim lim cos sin tan cot arcsin arccos arctan

∫ ∫ ∫ ∫ ∫ ∬ ∬ ∬ ∬ ∬ ∭ ∭ ∭ ∭ ∭ ⨌ ⨌ ⨌ ⨌ ⨌

∑ ∑ ∑ ∑ ∑ ∮ ∮ ∮ ∮ ∮ ∏ ∏ ∏ ∏ ∏ ∐ ∐ ∐ ∐ ∐

+ - × ÷ ± ∓ = ∪ ∩ ≠ ∼ ≈ ∅ ∀ ∃ ∈ ∋ ∝ ≤ ≥ ≃ ≅ ≡ < > ≪ ≫ ⊂ ∉ ⊃ ⊆ ⊇ ⇒ ⇐ ⇔ ⇒ ⇐ ⇔ ⇑ ⇓ ⇕ → ← ↔ → ← ↔ ↑ ↓ ↕ ↖ ↗ ↘ ↙ ↪ ↩ ⇀ ↼ ⇁ ↽

° ∂ ∞ α β γ δ θ λ μ ν ξ π ρ σ φ ω ε ƒ κ τ υ Γ Δ Λ Σ Π Ω

Close [X]

Differentiation Silly Question

2 Answers

Your Answer

Add Image

Similar Questions