The World of Numbers | Exercise 3.3

Question 6

Show that:

(12+34)×83=12×83+34×83\left(\frac{1}{2} + \frac{3}{4}\right) \times \frac{8}{3} = \frac{1}{2} \times \frac{8}{3} + \frac{3}{4} \times \frac{8}{3}

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Solution

We will calculate both sides of the equation separately.

Step 1 — Calculate the Left Side

Let's find the value of the left side. First, we add the fractions inside the bracket. We find a common denominator for 2 and 4.

12+34=1×22×2+34\frac{1}{2} + \frac{3}{4} = \frac{1 \times 2}{2 \times 2} + \frac{3}{4}

=24+34= \frac{2}{4} + \frac{3}{4}

=2+34= \frac{2+3}{4}

=54= \frac{5}{4}

Now, we multiply this sum by 83\frac{8}{3}.

(54)×83=5×84×3\left(\frac{5}{4}\right) \times \frac{8}{3} = \frac{5 \times 8}{4 \times 3}

=4012= \frac{40}{12}

We simplify the fraction by dividing by 4.

103\boxed{\frac{10}{3}}

Diagram 1

Step 2 — Calculate the Right Side

Let's find the value of the right side. First, we multiply 12\frac{1}{2} by 83\frac{8}{3}.

12×83=1×82×3\frac{1}{2} \times \frac{8}{3} = \frac{1 \times 8}{2 \times 3}

=86= \frac{8}{6}

We simplify this fraction by dividing by 2.

=43= \frac{4}{3}

Next, we multiply 34\frac{3}{4} by 83\frac{8}{3}.

34×83=3×84×3\frac{3}{4} \times \frac{8}{3} = \frac{3 \times 8}{4 \times 3}

=2412= \frac{24}{12}

We simplify this fraction by dividing by 12.

=2= 2

Finally, we add these two results.

43+2=43+2×33\frac{4}{3} + 2 = \frac{4}{3} + \frac{2 \times 3}{3}

=43+63= \frac{4}{3} + \frac{6}{3}

=4+63= \frac{4+6}{3}

103\boxed{\frac{10}{3}}

Answer

(i) The left side of the equation is 103\frac{10}{3}. (ii) The right side of the equation is 103\frac{10}{3}. (iii) Since both sides are equal to 103\frac{10}{3}, the given statement is shown to be true.

More questions in Exercise 3.3

Q1

Prove that the following rational numbers are equal:

(i) 23\frac{2}{3} and 46\frac{4}{6} (ii) 54\frac{5}{4} and 108\frac{10}{8} (iii) 35-\frac{3}{5} and 610-\frac{6}{10} (iv) 93\frac{9}{3} and 33

Q2

Find the sum:

(i) 25+310\frac{2}{5} + \frac{3}{10} (ii) 712+58\frac{7}{12} + \frac{5}{8} (iii) 47+314-\frac{4}{7} + \frac{3}{14}

Q3

Find the difference:

(i) 5614\frac{5}{6} - \frac{1}{4} (ii) 11834\frac{11}{8} - \frac{3}{4} (iii) 79(23)-\frac{7}{9} - \left(-\frac{2}{3}\right)

Q4

Find the product:

(i) 23×310\frac{2}{3} \times \frac{3}{10} (ii) 711×58\frac{7}{11} \times \frac{5}{8} (iii) 47×514-\frac{4}{7} \times \frac{5}{14}

Q5

Find the quotient:

(i) 23÷310\frac{2}{3} \div \frac{3}{10} (ii) 711÷58\frac{7}{11} \div \frac{5}{8} (iii) 47÷514-\frac{4}{7} \div \frac{5}{14}

Q6

Show that:

(12+34)×83=12×83+34×83\left(\frac{1}{2} + \frac{3}{4}\right) \times \frac{8}{3} = \frac{1}{2} \times \frac{8}{3} + \frac{3}{4} \times \frac{8}{3}

Q7

Simplify the following using the distributive property:

79(6734)\frac{7}{9}\left(\frac{6}{7} - \frac{3}{4}\right)

Q8

Find the rational number xx such that:

56(x+35)=56x+12\frac{5}{6}\left(x + \frac{3}{5}\right) = \frac{5}{6}x + \frac{1}{2}

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