Selina solutions

Selina solutions

Grade 7

Rational Numbers | Exercise 2(D)

Question 1

Q1) Evaluate:

(i)

\frac{5}{4}\times\frac{3}{7}

(ii) \frac{2}{3}\times\left(-\frac{6}{7}\right)

(iii) \frac{-12}{5}\times\frac{10}{-3}

(iv) \frac{-45}{39}\times\frac{-13}{15}

(v) 3\frac{1}{8}\times\left(-2\frac{2}{5}\right)

(vi) 2\frac{14}{24}\times\frac{-5}{16}

(vii) \frac{-8}{9}\times\frac{-3}{16}

(viii) \frac{5}{-27}\times\frac{-9}{20}

Solution 1:

(i) \frac{5}{4}\times\frac{3}{7}

=\frac{5\times3}{4\times7}=\frac{15}{28}

(ii) \frac{2}{3}\times\left(-\frac{6}{7}\right)

=\frac{2\times\left(-6\right)}{3\ \times7}=\frac{2\times\left(-2\right)}{7}=\frac{-4}{7}

(iii) \frac{-12}{5}\times\frac{10}{-3}

\frac{-12\times10}{5\times\left(-3\right)}=4\times2=8

(iv) \frac{-45}{39}\times\frac{-13}{15}

= \frac{-45\times\left(-13\right)}{39\times15}=\frac{-3}{-3}=1

(v) 3\frac{1}{8}\times\left(-2\frac{2}{5}\right)

= \frac{25}{8}\times\frac{-12}{5}

= \frac{25\times\left(-12\right)}{8\times5}=\frac{5\times\left(-3\right)}{2}=\frac{-15}{2}

(vi) 2\frac{14}{24}\times\frac{-5}{16}

= \frac{64}{25}\times\frac{-5}{16}

= \frac{64\times\left(-5\right)}{25\times16}=\frac{4\times\left(-1\right)}{5}=\frac{-4}{5}

(vii) \frac{-8}{9}\times\frac{-3}{16}

= \frac{-8\times\left(-3\right)}{9\times16}=\frac{-1\times\left(-1\right)}{3\times2}=\frac{1}{6}

(viii) \frac{5}{-27}\times\frac{-9}{20}

= \frac{5\times\left(-9\right)}{-27\times20}=\frac{1}{3\times4}=\frac{1}{12}

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subject-cta

Question 1

Q1) Evaluate:

(i)

\frac{5}{4}\times\frac{3}{7}

(ii) \frac{2}{3}\times\left(-\frac{6}{7}\right)

(iii) \frac{-12}{5}\times\frac{10}{-3}

(iv) \frac{-45}{39}\times\frac{-13}{15}

(v) 3\frac{1}{8}\times\left(-2\frac{2}{5}\right)

(vi) 2\frac{14}{24}\times\frac{-5}{16}

(vii) \frac{-8}{9}\times\frac{-3}{16}

(viii) \frac{5}{-27}\times\frac{-9}{20}

Solution 1:

(i) \frac{5}{4}\times\frac{3}{7}

=\frac{5\times3}{4\times7}=\frac{15}{28}

(ii) \frac{2}{3}\times\left(-\frac{6}{7}\right)

=\frac{2\times\left(-6\right)}{3\ \times7}=\frac{2\times\left(-2\right)}{7}=\frac{-4}{7}

(iii) \frac{-12}{5}\times\frac{10}{-3}

\frac{-12\times10}{5\times\left(-3\right)}=4\times2=8

(iv) \frac{-45}{39}\times\frac{-13}{15}

= \frac{-45\times\left(-13\right)}{39\times15}=\frac{-3}{-3}=1

(v) 3\frac{1}{8}\times\left(-2\frac{2}{5}\right)

= \frac{25}{8}\times\frac{-12}{5}

= \frac{25\times\left(-12\right)}{8\times5}=\frac{5\times\left(-3\right)}{2}=\frac{-15}{2}

(vi) 2\frac{14}{24}\times\frac{-5}{16}

= \frac{64}{25}\times\frac{-5}{16}

= \frac{64\times\left(-5\right)}{25\times16}=\frac{4\times\left(-1\right)}{5}=\frac{-4}{5}

(vii) \frac{-8}{9}\times\frac{-3}{16}

= \frac{-8\times\left(-3\right)}{9\times16}=\frac{-1\times\left(-1\right)}{3\times2}=\frac{1}{6}

(viii) \frac{5}{-27}\times\frac{-9}{20}

= \frac{5\times\left(-9\right)}{-27\times20}=\frac{1}{3\times4}=\frac{1}{12}

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