Question : If $a − b = 8$ and $ab = 9$, then the value of $a + b$ is ______.
Option 1: $\pm 9$
Option 2: $\pm 7$
Option 3: $\pm 8$
Option 4: $\pm 10$
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Correct Answer: $\pm 10$
Solution : Given, $a − b = 8$ and $ab = 9$ Consider, $a-b = 8$ Squaring both sides, ⇒ $a^2 + b^2 - 2ab = 64$ ⇒ $a^2 + b^2 - 2\times 9 = 64$ ⇒ $a^2 + b^2 = 64+ 18$ ⇒ $a^2 + b^2 = 82$ Now we have to find $a+b$ $(a+b)^2 = a^2 + b^2 + 2ab$ $= 87 + 2\times 9$ $=82 + 18$ $= 100$ ⇒ $a+b = \sqrt{100}$ ⇒ $a+b = \pm 10$ Hence, the correct answer is $\pm 10$.
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Question : If $x+y+z = 9$, then the value of $(x−4)^3+(y−2)^3+(z−3)^3−3(x−4)(y−2)(z−3)$ is:
Option 1: 6
Option 2: 9
Option 3: 0
Option 4: 1
Question : If A : B = 2 : 3 and B : C = 3 : 7, then (A + B) : (B + C) : (C + A) is:
Option 1: 4 : 8 : 9
Option 2: 5 : 8 : 9
Option 3: 5 : 10 : 9
Option 4: 4 : 10 : 9
Question : Find the value of the given expression: $10 \div 5 × 1+3 - [8 - \{5 - (7 - 7 - 9)\}]$
Option 1: 11
Option 2: 10
Option 3: 9
Option 4: 8
Question : If $a^3=117+b^3$ and $a=3+b$, then the value of $(a+b)$ is:
Option 1: $\pm 7$
Option 2: $\pm 49$
Option 3: $\pm 13$
Option 4: $0$
Question : If $3\sqrt{\frac{1-a}{a}}+9=19-3\sqrt{\frac{a}{1-a}};$ then, what is the value of $a?$
Option 1: $\frac{3}{10}$ and $\frac{7}{10}$
Option 2: $\frac{1}{10}$ and $\frac{9}{10}$
Option 3: $\frac{2}{5}$ and $\frac{3}{5}$
Option 4: $\frac{1}{5}$ and $\frac{4}{5}$
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