Questions · Page 2 of 3

[2 Mark Question Answer]

Question 522 Marks
Using the standard formulae, expand:
$\left(6+\frac{5}{x}\right)^2$
Answer
$36+\frac{25}{x^2}+\frac{60}{x}$
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Question 532 Marks
Using the standard formulae, expand:
$\left(\frac{x}{3}+\frac{6}{x}\right)^2$
Answer
$\frac{x^2}{9}+\frac{36}{x^2}+4$
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Question 542 Marks
Using the standard formulae, expand:
$\left(\frac{2}{5} x+\frac{5}{6} y\right)^2$
Answer
$\frac{4}{25} x^2+\frac{25}{36} y^2+\frac{2}{3} x y$
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Question 552 Marks
Using the standard formulae, expand:
$\left(2 x+\frac{1}{3 x}\right)^2$
Answer
$4 x^2+\frac{1}{9 x^2}+\frac{4}{3}$
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Question 582 Marks
If $a=\frac{1}{(a-5)}$, where $a \neq 5$ and $a \neq 0$, find the values of :  $\left(a^2+\frac{1}{a^2}\right)$
Answer
$3 \sqrt{3}$
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Question 592 Marks
If $a=\frac{1}{(a-5)}$, where $a \neq 5$ and $a \neq 0$, find the values of : $\left(a^2-\frac{1}{a^2}\right)$
Answer
$\pm 5 \sqrt{29}$
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Question 602 Marks
If $a=\frac{1}{(a-5)}$, where $a \neq 5$ and $a \neq 0$, find the values of : $\left(a+\frac{1}{a}\right)$
Answer
$\pm \sqrt{29}$
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Question 612 Marks
If $a=\frac{1}{(a-5)}$, where $a \neq 5$ and $a \neq 0$, find the values of : $\left(a-\frac{1}{a}\right)$
Answer
5
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Question 622 Marks
If $\left(a^2-4 a-1\right)=0$ and $a \neq 0$, find the values of :  $\left(a^2+\frac{1}{a^2}\right)$
Answer
18
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Question 632 Marks
If $\left(a^2-4 a-1\right)=0$ and $a \neq 0$, find the values of :$\left(a^2-\frac{1}{a^2}\right)$
Answer
$\pm 8 \sqrt{5}$
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Question 642 Marks
If $\left(a^2-4 a-1\right)=0$ and $a \neq 0$, find the values of : $\left(a+\frac{1}{a}\right)$
Answer
$\pm 2 \sqrt{5}$
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Question 712 Marks
Simplify : $\left(3 x-\frac{1}{3 x}\right)^2-\left(3 x+\frac{1}{3 x}\right)\left(3 x-\frac{1}{3 x}\right)$
Answer
$2\left(\frac{1}{9 x^2}-1\right)$
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Question 722 Marks
Simplify : $\left(\frac{a}{2 b}+\frac{2 b}{a}\right)^2-\left(\frac{2 b}{a}-\frac{a}{2 b}\right)^2$
Answer
4
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Question 742 Marks
Simplify : $\left(x+\frac{1}{x}\right)^2+\left(x-\frac{1}{x}\right)^2$
Answer
$2\left(x^2+\frac{1}{x^2}\right)$
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Question 772 Marks
Using the standard formulae, expand:
$(x-5)(2 x-1)(2 x+3)$
Answer
$4 x^3-16 x^2-23 x+15$
[Hint.
$\begin{aligned}(x-5)(2 x-1)(2 x+3) & =(x-5)\left[4 x^2+6 x-2 x-3\right] \\ & =(x-5)\left(4 x^2+4 x-3\right) \\ & =x\left(4 x^2+4 x-3\right)-5\left(4 x^2+4 x-3\right) \text { etc.] }\end{aligned}$
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Question 812 Marks
Using the standard formulae, expand:
$\left(2 x^2+\frac{3}{x^2}\right)\left(2 x^2-\frac{3}{x^2}\right)$
Answer
$4 x^4-\frac{9}{x^4}$
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Question 822 Marks
Using the standard formulae, expand:
$\left(5 x+\frac{1}{5 x}\right)\left(5 x-\frac{1}{5 x}\right)$
Answer
$25 x^2-\frac{1}{25 x^2}$
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Question 882 Marks
If $\frac{1}{x+y}=\frac{1}{x}+\frac{1}{y},(x \neq 0, y \neq 0, x \neq y)$, then find the value of $x^3-y^3$.
Answer
0
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Question 902 Marks
Write down the following product:
$\left(3 a^2-b^2\right)\left(2 a^2+5 b^2\right)$
Answer
$6 a^4+13 a^2 b^2-5 b^4$
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Question 962 Marks
Write down the following product:
$\left(x^2+1\right)\left(x^3+2\right)$ [Hint. Put $\left.x^2=y\right]$
Answer
$x^4+3 x^2+2$
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[2 Mark Question Answer] - Page 2 - MATHEMATICS STD 9 Questions - Vidyadip