Relations

If R is a binary relation on a set A define R–1 on A. Let R = {(a, b) : a, b ϵ W and 3a + 2b = 15} and 3a + 2b = 15}, where W is the set of whole numbers. Express R and R–1 as sets of ordered pairs. Show that
(i) dom (R) = range (R–1)
(ii) range (R) = dom (R–1)

Answer : 3a + 2b = 15 a=1 è b=6 a=3 è b=3 a=5 è b=0 R = {(1, 6), (3, 3), (5, 0)} ????−1 = {(6, 1), (3, 3), (0, 5)} The domain of R is the set of first co-ordinates of R Dom(R) = {1, 3, 5} The range...

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Find the domain and range of each of the relations given below: (i) R = {(–1, 1), (1, 1), (–2, 4), (2, 4), (2, 4), (3, 9)}
(ii)R ={(x, y) : x + 2y = 8 and x, y ϵ N}
(iii) R = {(x, y), : y = |x – 1|, x ϵ Z and |x| ≤ 3}

Answer : (i) Given: R = {(–1, 1), (1, 1), (–2, 4), (2, 4), (2, 4), (3, 9)} Dom(R) = {x: (x, y)    R} = {-2, -1, 1, 2, 3} Range(R) = {y: (x, y)    R} = {1, 4, 9}   (ii) Given: R = {(x, y): x +...

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Let A = {a, b, c, d}, B = {c, d, e} and C = {d, e, f, g}. Then verify each of the following identities: (i) A × (B ∩ C) = (A × B) ∩ (A × C) (ii) A × (B – C) = (A × B) – (A × C) (iii) (A × B) ∩ (B × A) = (A ∩ B) × (A ∩ B)

Answer : Given: A = {a, b, c, d,}, B = {c, d, e} and C = {d, e, f, g} Need to prove: A × (B ∩ C) = (A × B) ∩ (A × C) Left hand side, (B ∩ C) = {d, e} ⇒ A × (B ∩ C) = {(a, d), (a, e), (b, d), (b, e),...

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On dividing a polynomial $\mathrm{p}(\mathrm{x})$ by a non-zero polynomial $\mathrm{q}(\mathrm{x}), \operatorname{let} \mathrm{g}(\mathrm{x})$ be the quotient and $\mathrm{r}(\mathrm{x})$ be the remainder, then $\mathrm{p}(\mathrm{x})=\mathrm{q}(\mathrm{x}) \cdot \mathrm{g}(\mathrm{x})+\mathrm{r}(\mathrm{x})$, where (a) $\mathrm{r}(\mathrm{x})=0$ always (b) $\operatorname{deg} \mathrm{r}(\mathrm{x})<\operatorname{deg} \mathrm{g}(\mathrm{x})$ always (c) either $\mathrm{r}(\mathrm{x})=0$ or $\operatorname{deg} \mathrm{r}(\mathrm{x})<\operatorname{deg} \mathrm{g}(\mathrm{x})$ (d) $r(x)=g(x)$

The correct option is (c) either $\mathrm{r}(\mathrm{x})=0$ or $\operatorname{deg} \mathrm{r}(\mathrm{x})<\operatorname{deg} \mathrm{g}(\mathrm{x})$ By division algorithm on polynomials, either...

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If $\alpha, \beta, \gamma$ be the zeroes of the polynomial $p(x)$ such that $(\alpha+\beta+\gamma)=3,(\alpha \beta+\beta \gamma+\gamma \alpha)$ $=-10$ and $\alpha \beta \gamma=-24$, then $\mathrm{p}(\mathrm{x})=?$ (a) $x^{3}+3 x^{2}-10 x+24$ (b) $x^{3}+3 x^{2}+10 x-24$ (c) $x^{3}-3 x^{2}-10 x+24$ (d) none of these

The correct option is option (c) $x^{3}-3 x^{2}-10 x+24$ $\alpha, \beta$ and $\gamma$ are the zeroes of polynomial $p(x)$. $(\alpha+\beta+\gamma)=3,(\alpha \beta+\beta \gamma+\gamma \alpha)=-10$ and...

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