Tamilnadu State Board New Syllabus Samacheer Kalvi 8th Maths Guide Pdf Chapter 1 Numbers Ex 1.2 Textbook Questions and Answers, Notes.

## Tamilnadu Samacheer Kalvi 8th Maths Solutions Chapter 1 Numbers Ex 1.2

Question 1.

Fill in the blanks:

(i) The value of \(\frac{-5}{12}+\frac{7}{15}\) = ________ .

Answer:

\(\frac{1}{20}\)

(ii) The value of \(\left(\frac{-3}{6}\right) \times\left(\frac{18}{-9}\right)\) is = ________ .

Answer:

1

(iii) The value of \(\left(\frac{-15}{23}\right) \div\left(\frac{30}{-46}\right)\) is ________ .

Answer:

1

(iv) The rational number ________ does not have a reciprocal.

Answer:

0

(v) The multiplicative inverse of -1 is ________ .

Answer:

-1

Question 2.

Say True or False

(i) All rational numbers have an additive inverse.

Answer:

True

(ii) The rational numbers that are equal to their additive inverses are 0 and -1.

Answer:

False

(iii) The additive inverse of \(\frac{-11}{-17}\) is \(\frac{11}{17}\)

Answer:

False

(iv) The rational number which is its own reciprocal is -1.

Answer:

True

(v) The multiplicative inverse exists for all rational numbers.

Answer:

False

Question 3.

Find the sum

(i) \(\frac{7}{5}+\frac{3}{5}\)

(ii) \(\frac{7}{5}+\frac{5}{7}\)

(iii) \(\frac{6}{5}+\left(\frac{-14}{15}\right)\)

(iv) \(-4 \frac{2}{3}+7 \frac{5}{12}\)

Answer:

(i) \(\frac{7}{5}+\frac{3}{5}\)

(ii) \(\frac{7}{5}+\frac{5}{7}\)

(iii) \(\frac{6}{5}+\left(\frac{-14}{15}\right)\)

(iv) \(-4 \frac{2}{3}+7 \frac{5}{12}\)

Question 4.

Subtract \(\frac{-8}{44}\) from \(\frac{-17}{11}\)

Answer:

Question 5.

Evaluate

(i) \(\frac{9}{132} \times \frac{-11}{3}\)

(ii) \(\frac{-7}{27} \times \frac{24}{-35}\)

Answer:

(i) \(\frac{9}{132} \times \frac{-11}{3}\)

(ii) \(\frac{-7}{27} \times \frac{24}{-35}\)

Question 6.

Divide

(i) \(\frac{-21}{5}\) by \(\frac{-7}{-10}\)

(ii) \(\frac{-3}{13}\) by -3

(iii) -2 by \(\frac{-6}{15}\)

Answer:

(i) \(\frac{-21}{5}\) by \(\frac{-7}{-10}\)

(ii) \(\frac{-3}{13}\) by -3

(iii) -2 by \(\frac{-6}{15}\)

Question 7.

Find (a + b) ÷ (a – b) if

(i) a = \(\frac{1}{2}\), b = \(\frac{2}{3}\)

(ii) a = \(\frac{-3}{5}\), b = \(\frac{2}{15}\)

Answer:

(i) a = \(\frac{1}{2}\), b = \(\frac{2}{3}\)

(ii) a = \(\frac{-3}{5}\), b = \(\frac{2}{15}\)

Question 8.

Simplify \(\frac{1}{2}+\left(\frac{3}{2}-\frac{2}{5}\right) \div \frac{3}{10} \times 3\) and show that it is a rational number between 11 and 12.

Answer:

Question 9.

Simplify

(i) \(\left[\frac{11}{8} \times\left(\frac{-6}{33}\right)\right]+\left[\frac{1}{3}+\left(\frac{3}{5} \div \frac{9}{20}\right)\right]-\left[\frac{4}{7} \times \frac{-7}{5}\right]\)

(ii) \(\left[\frac{4}{3} \div\left(\frac{8}{-7}\right)\right]-\left[\frac{3}{4} \times \frac{4}{3}\right]+\left[\frac{4}{3} \times\left(\frac{-1}{4}\right)\right]\)

Answer:

(i) \(\left[\frac{11}{8} \times\left(\frac{-6}{33}\right)\right]+\left[\frac{1}{3}+\left(\frac{3}{5} \div \frac{9}{20}\right)\right]-\left[\frac{4}{7} \times \frac{-7}{5}\right]\)

(ii) \(\left[\frac{4}{3} \div\left(\frac{8}{-7}\right)\right]-\left[\frac{3}{4} \times \frac{4}{3}\right]+\left[\frac{4}{3} \times\left(\frac{-1}{4}\right)\right]\)

Question 10.

A student had multiplied a number by \(\frac{4}{3}\) instead of dividing it by \(\frac{4}{3}\) and got 70 more than the correct answer. Find the number.

Answer:

Let the number = a

Objective Type Questions

Question 11.

The standard form of the sum \(\) is ________ .

(A) 1

(B) \(\frac{-1}{2}\)

(C) \(\frac{1}{12}\)

(D) \(\frac{1}{22}\)

Answer:

1

Hint:

Question 12.

\(\left(\frac{3}{4}-\frac{5}{8}\right)+\frac{1}{2}\) = _______ .

(A) \(\frac{15}{64}\)

(B) 1

(C) \(\frac{5}{8}\)

(D) \(\frac{1}{16}\)

Answer:

(C) \(\frac{5}{8}\)

Hint:

Question 13.

\(\frac{3}{4}+\left(\frac{5}{8}+\frac{1}{2}\right)\) =

(A) \(\frac{13}{10}\)

(B) \(\frac{2}{3}\)

(C) \(\frac{3}{2}\)

(D) \(\frac{5}{8}\)

Answer:

(B) \(\frac{2}{3}\)

Hint:

Question 14.

\(\) = _______ .

(A) \(\frac{5}{8}\)

(B) \(\frac{2}{3}\)

(C) \(\frac{15}{32}\)

(D) \(\frac{15}{16}\)

Answer:

(D) \(\frac{15}{16}\)

Hint:

Question 15.

Which of these rational number which have additive inverse?

(A) 7

(B) \(\frac{-5}{7}\)

(C) 0

(D) all of these

Answer:

(D) all of these

Hint:

Additive inverse of 7 is -7

Additive inverse of \(\frac{-5}{7}\) is \(\frac{5}{7}\)

Additive inverse of 0 is 0