Simplifying Rational Numbers and Identifying Multiplicative Properties

MathematicsProperties of Rational NumbersEasy

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9. Use the distributivity of multiplication of rational numbers over addition to simplify :

(a) $\frac{-3}{8} \times \left( \frac{4}{7} + \frac{-11}{7} \right)$

(b) $\frac{-2}{5} \times \left( \frac{3}{8} - 25 \right)$

(c) $\frac{7}{4} \times \left( \frac{5}{8} + \frac{1}{2} \right)$

10. What two properties of multiplication are involved, if we wish to show that $5 \times \frac{1}{5} a = a$?

11. Find $a$, if $a$ is a rational number and $a \times a = a$.

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Step by Step Written Solution

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Step 1

In this problem, we are asked to simplify three expressions using the distributive property of multiplication over addition for rational numbers.

Distributive Property of Multiplication over Addition

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Step 2

The distributive property states that a times the sum of b and c is equal to a times b plus a times c.

$$a \times (b + c) = (a \times b) + (a \times c)$$
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Step 3

Let's solve part a. We have negative three eighths times the sum of four sevenths and negative eleven sevenths.

Part (a)

$$\frac{-3}{8} \times \left( \frac{4}{7} + \frac{-11}{7} \right)$$
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Step 4

Using the distributive property, we multiply negative three eighths with each term inside the parentheses.

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Step 5

Now we simplify each term. For the first term, negative three times four is negative twelve, and eight times seven is fifty-six. Similarly, for the second term, negative three times negative eleven is positive thirty-three, and eight times seven is fifty-six.

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Step 6

Since they have a common denominator, we add the numerators. Negative twelve plus thirty-three leaves us with twenty-one over fifty-six.

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Step 7

We can simplify this by dividing both numerator and denominator by their greatest common divisor, which is seven. This gives us three eighths.

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Step 8

Moving on to part b, we have negative two fifths times the difference of three eighths and twenty-five. Since subtraction is adding a negative, we can still use the distributive rule.

Part (b)

$$\frac{-2}{5} \times \left( \frac{3}{8} - 25 \right)$$
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Step 9

Distributing negative two fifths, we get negative two fifths times three eighths, minus negative two fifths times twenty-five.

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About This Question

Subject
Mathematics
Topic
Properties of Rational Numbers
Difficulty
Easy
Question Type
Open Ended

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