Factoriser Expressions
1. Problem statement: Factorize the given expressions:
- $C = x^2 - 9$
- $D = (4 + x)(2x - 1) + 2(4 + x)$
- $E = 49x^2 + 14x + 1 + 3(7x + 1)$
- $F = (\sqrt{2}x - 1)(x - 3) + \left(x - \frac{1}{\sqrt{2}}\right)(x - 1)$
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2. Factorize $C = x^2 - 9$:
This is a difference of squares:
$$x^2 - 9 = (x)^2 - (3)^2 = (x - 3)(x + 3)$$
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3. Factorize $D = (4 + x)(2x - 1) + 2(4 + x)$:
Factor $(4 + x)$ from both terms:
$$D = (4 + x)(2x - 1) + 2(4 + x) = (4 + x)((2x - 1) + 2)$$
Simplify inside the parenthesis:
$$(2x - 1) + 2 = 2x + 1$$
So:
$$D = (4 + x)(2x + 1)$$
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4. Factorize $E = 49x^2 + 14x + 1 + 3(7x + 1)$:
First, expand the last term:
$$3(7x + 1) = 21x + 3$$
Add this to the rest:
$$E = 49x^2 + 14x + 1 + 21x + 3 = 49x^2 + (14x + 21x) + (1 + 3) = 49x^2 + 35x + 4$$
Now, factor $E = 49x^2 + 35x + 4$.
Look for two numbers whose product is $49 \times 4 = 196$ and sum is $35$.
These numbers are $28$ and $7$ because $28 \times 7 = 196$ and $28 + 7 = 35$.
Rewrite:
$$49x^2 + 28x + 7x + 4$$
Group:
$$(49x^2 + 28x) + (7x + 4)$$
Factor each group:
$$7x(7x + 4) + 1(7x + 4)$$
Factor out common term $(7x + 4)$:
$$(7x + 4)(7x + 1)$$
So,
$$E = (7x + 4)(7x + 1)$$
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5. Factorize $F = (\sqrt{2}x - 1)(x - 3) + \left(x - \frac{1}{\sqrt{2}}\right)(x - 1)$:
First, expand each product:
$$ (\sqrt{2}x - 1)(x - 3) = \sqrt{2}x^2 - 3\sqrt{2}x - x + 3 $$
$$ \left(x - \frac{1}{\sqrt{2}}\right)(x - 1) = x^2 - x - \frac{x}{\sqrt{2}} + \frac{1}{\sqrt{2}} $$
Now sum these:
$$ F = (\sqrt{2}x^2 - 3\sqrt{2}x - x + 3) + (x^2 - x - \frac{x}{\sqrt{2}} + \frac{1}{\sqrt{2}}) $$
Group like terms:
Quadratic terms:
$$ \sqrt{2}x^2 + x^2 = (\sqrt{2} + 1)x^2 $$
Linear terms:
$$ -3\sqrt{2}x - x - x - \frac{x}{\sqrt{2}} = -3\sqrt{2}x - 2x - \frac{x}{\sqrt{2}} $$
Constants:
$$ 3 + \frac{1}{\sqrt{2}} $$
Rewrite linear terms with common factor x:
$$ x \left(-3\sqrt{2} - 2 - \frac{1}{\sqrt{2}}\right) $$
So,
$$ F = (\sqrt{2} + 1)x^2 + x \left(-3\sqrt{2} - 2 - \frac{1}{\sqrt{2}}\right) + 3 + \frac{1}{\sqrt{2}} $$
This expression does not simplify nicely by common factoring. Hence, $F$ is simplified as the above expression.
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Final factorized forms:
- $C = (x - 3)(x + 3)$
- $D = (4 + x)(2x + 1)$
- $E = (7x + 4)(7x + 1)$
- $F = (\sqrt{2} + 1)x^2 + x \left(-3\sqrt{2} - 2 - \frac{1}{\sqrt{2}}\right) + 3 + \frac{1}{\sqrt{2}}$