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Linear Equation in One Variable Questions and Answers



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Q1. $20 = 6 + 2\text{x}$


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$\Rightarrow 20 = 6 + 2\text{x}$

$\Rightarrow 20 - 6 = 2\text{x}$

$\Rightarrow 14 = 2\text{x}$

$\therefore \text{x} = \dfrac{14}{2} = 7$ Ans


Q2. $15 + \text{x} = 5\text{x} + 3$


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$\Rightarrow 15 + \text{x} = 5\text{x} + 3$

$\Rightarrow 15 - 3 = 5\text{x} - \text{x}$

$\Rightarrow 12 = 4\text{x}$

$\therefore \text{x} = \dfrac{12}{4} = 3$ Ans


Q3. $\dfrac{3\text{x} + 2}{\text{x} - 6} = -7$


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$\Rightarrow \dfrac{3\text{x} + 2}{\text{x} - 6} = -7$

$\Rightarrow 3\text{x} + 2 = -7(\text{x} - 6)$

$\Rightarrow 3\text{x} + 2 = -7\text{x} + 42$

$\Rightarrow 3\text{x} + 7\text{x} = 42 - 2$

$\Rightarrow 10\text{x} = 40$

$\therefore \text{x} = \dfrac{40}{10} = 4$ Ans


Q4. $3\text{a} - 4 = 2(4 - \text{a})$


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$\Rightarrow 3\text{a} - 4 = 2(4 - \text{a})$

$\Rightarrow 3\text{a} - 4 = 8 - 2\text{a}$

$\Rightarrow 3\text{a} + 2\text{a} = 8 + 4$

$\Rightarrow 5\text{a} = 12$

$\therefore \text{a} = \dfrac{12}{5} = 2.4$ Ans


Q5. $3(\text{b} - 4) = 2(4 - \text{b})$


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$\Rightarrow 3(\text{b} - 4) = 2(4 - \text{b})$

$\Rightarrow 3\text{b} - 12 = 8 - 2\text{b}$

$\Rightarrow 3\text{b} + 2\text{b} = 8 + 12$

$\Rightarrow 5\text{b} = 20$

$\therefore \text{b} = \dfrac{20}{5} = 4$ Ans


Q6. $\dfrac{\text{x} + 2}{9} = \dfrac{\text{x} + 4}{11}$


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$\Rightarrow \dfrac{\text{x} + 2}{9} = \dfrac{\text{x} + 4}{11}$

$\Rightarrow 11(\text{x} + 2) = 9(\text{x} + 4)$

$\Rightarrow 11\text{x} - 9\text{x} = 36 - 22$

$\Rightarrow 2\text{x} = 14$

$\therefore \text{x} = \dfrac{14}{2} = 7$ Ans


Q7. $\dfrac{\text{x} - 8}{5} = \dfrac{\text{x} - 12}{9}$


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$\Rightarrow \dfrac{\text{x} - 8}{5} = \dfrac{\text{x} - 12}{9}$

$\Rightarrow 9(\text{x} - 8) = 5(\text{x} - 12)$

$\Rightarrow 9\text{x} - 72 = 5\text{x} - 60$

$\Rightarrow 9\text{x} - 5\text{x} = 72 - 60$

$\Rightarrow 4\text{x} = 12$

$\therefore \text{x} = \dfrac{12}{4} = 3$ Ans


Q8. $5(8\text{x} + 3) = 9(4\text{x} + 7)$


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$\Rightarrow 5(8\text{x} + 3) = 9(4\text{x} + 7)$

$\Rightarrow 40\text{x} + 15 = 36\text{x} + 63$

$\Rightarrow 40\text{x} - 36\text{x} = 63 - 15$

$\Rightarrow 4\text{x} = 48$

$\therefore \text{x} = \dfrac{48}{4} = 12$ Ans


Q9. $3(\text{x} + 1) = 12 + 4(\text{x} - 1)$


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$\Rightarrow 3(\text{x} + 1) = 12 + 4(\text{x} - 1)$

$\Rightarrow 3\text{x} + 3 = 12 + 4\text{x} - 4$

$\Rightarrow 3\text{x} + 3 = 4\text{x} + 8$

$\Rightarrow 3 - 8 = 4\text{x} - 3\text{x}$

$\therefore \text{x} = -5$ Ans


Q10. $\dfrac{3\text{x}}{4} - \dfrac{\text{1}}{4}(\text{x} - 20) = \dfrac{\text{x}}{4} + 32$


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$\Rightarrow \dfrac{3\text{x}}{4} - \dfrac{\text{1}}{4}(\text{x} - 20) = \dfrac{\text{x}}{4} + 32$

$\Rightarrow \dfrac{3\text{x}}{4} - \dfrac{\text{x} - 20}{4} = \dfrac{\text{x}}{4} + 32$

Simplify by taking L.C.M. = 4

$\Rightarrow 4(\dfrac{3\text{x}}{4}) - 4(\dfrac{\text{x} - 20}{4}) = 4(\dfrac{\text{x}}{4}) + 4(32)$

$\Rightarrow 3\text{x} - \text{x} - 20 = \text{x} + 128$

$\Rightarrow 2\text{x} - 20 = \text{x} + 128$

$\Rightarrow 2\text{x} - \text{x} = 128 - 20$

$\therefore \text{x} = 108$ Ans


Q11. $3\text{a} - \dfrac{1}{5} = \dfrac{\text{a}}{5} + 5\dfrac{2}{5}$


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$\Rightarrow 3\text{a} - \dfrac{1}{5} = \dfrac{\text{a}}{5} + 5\dfrac{2}{5}$

Simplify by taking L.C.M. = 5

$\Rightarrow 5(3\text{a}) - 5(\dfrac{1}{5}) = 5(\dfrac{\text{a}}{5}) + 5(\dfrac{27}{5})$

$\Rightarrow 15\text{a} - 1 = \text{a} + 27$

$\Rightarrow 15\text{a} - \text{a} = 27 + 1$

$\Rightarrow 14\text{a} = 28$

$\therefore \text{a} = \dfrac{28}{14} = 2$ Ans


Q12. $\dfrac{\text{x}}{3} - 2\dfrac{1}{2} = \dfrac{4\text{x}}{9} - \dfrac{2\text{x}}{3}$


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$\Rightarrow \dfrac{\text{x}}{3} - 2\dfrac{1}{2} = \dfrac{4\text{x}}{9} - \dfrac{2\text{x}}{3}$

$\Rightarrow \dfrac{\text{x}}{3} - \dfrac{5}{2} = \dfrac{4\text{x}}{9} - \dfrac{2\text{x}}{3}$

L.C.M. of denominators = 18

$\Rightarrow 18(\dfrac{\text{x}}{3}) - 18(\dfrac{5}{2}) = 18(\dfrac{4\text{x}}{9}) - 18(\dfrac{2\text{x}}{3})$

$\Rightarrow 6\text{x} - 9(5) = 2(4\text{x}) - 6(2\text{x})$

$\Rightarrow 6\text{x} - 45 = 8\text{x} - 12\text{x}$

$\Rightarrow 6\text{x} - 45 = -4\text{x}$

$\Rightarrow 6\text{x} + 4\text{x} = 45$

$\Rightarrow 10\text{x} = 45$

$\therefore \text{x} = \dfrac{45}{10} = 4.5$ Ans


Q13. $\dfrac{4(\text{y} + 2)}{5} = 7 + \dfrac{5\text{y}}{13}$


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$\Rightarrow \dfrac{4(\text{y} + 2)}{5} = 7 + \dfrac{5\text{y}}{13}$

$\Rightarrow \dfrac{4\text{y} + 8}{5} = 7 + \dfrac{5\text{y}}{13}$

L.C.M. of denominators = 65

$\Rightarrow 65(\dfrac{4\text{y} + 8}{5}) = 65(7) + 65(\dfrac{5\text{y}}{13})$

$\Rightarrow 13(4\text{y} + 8) = 455 + 5(5\text{y})$

$\Rightarrow 52\text{y} + 104 = 455 + 25\text{y}$

$\Rightarrow 52\text{y} - + 25\text{y} = 455 -104$

$\Rightarrow 27\text{y} = 351$

$\therefore \text{y} = \dfrac{351}{27} = 13$ Ans


Q14. $\dfrac{\text{a} + 5}{6} - \dfrac{\text{a} + 1}{9} = \dfrac{\text{a} + 3}{4}$


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$\Rightarrow \dfrac{\text{a} + 5}{6} - \dfrac{\text{a} + 1}{9} = \dfrac{\text{a} + 3}{4}$

L.C.M. of denominators = 36

$\Rightarrow 36(\dfrac{\text{a} + 5}{6}) - 36(\dfrac{\text{a} + 1}{9}) = 36(\dfrac{\text{a} + 3}{4})$

$\Rightarrow 6(\text{a} + 5) - 4(\text{a} + 1) = 9(\text{a} + 3)$

$\Rightarrow 6\text{a} + 30 - 4\text{a} - 4 = 9\text{a} + 27$

$\Rightarrow 2\text{a} + 26 = 9\text{a} + 27$

$\Rightarrow 26 - 27 = 9\text{a} - 2\text{a}$

$\Rightarrow -1 = 7\text{a}$

$\therefore \text{a} = -\dfrac{1}{7}$ Ans


Q15. $\dfrac{2\text{x} - 13}{5} - \dfrac{\text{x} - 3}{11} = \dfrac{\text{x} - 9}{5} + 1$


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$\Rightarrow \dfrac{2\text{x} - 13}{5} - \dfrac{\text{x} - 3}{11} = \dfrac{\text{x} - 9}{5} + 1$

L.C.M. of denominators = 55

$\Rightarrow 55(\dfrac{2\text{x} - 13}{5}) - 55(\dfrac{\text{x} - 3}{11}) = 55(\dfrac{\text{x} - 9}{5}) + 55(1)$

$\Rightarrow 11(2\text{x} - 13) - 5(\text{x} - 3) = 11(\text{x} - 9) + 55$

$\Rightarrow 22\text{x} - 143 - 5\text{x} + 15 = 11\text{x} - 99 + 55$

$\Rightarrow 17\text{x} - 128 = 11\text{x} - 44$

$\Rightarrow 17\text{x} - 11\text{x} = 128 - 44$

$\Rightarrow 6\text{x} = 128 - 44$

$\Rightarrow 6\text{x} = 84$

$\therefore \text{x} = \dfrac{84}{6} = 14$ Ans


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