Question

ajutor vă rog!!!!!!!!​

Answer 1

1) Inversul numarului 11 este $\displaystyle\\\frac{1}{11}$

2) $\displaystyle\\\rm \\5 \times 2\frac{1}{3} = 5 \times \frac{2 \times 3 + 1}{3} = 5 \times \frac{7}{3} = \frac{35}{3}$

3) $\displaystyle\\\rm\\1\frac{7}{8} \times 4\frac{3}{4} \times 32 = \frac{15}{8} \times\frac{4 \times 4 + 3}{4} \times 32$ $\displaystyle\\\rm\\= \frac{15}{8} \times \frac{15}{4} \times 32 = \frac{225}{32} \times 32 = 225$

4) $\displaystyle\\\rm\\\frac{1}{5} \times 2\frac{1}{2} \times 3= \frac{1}{5} \times \frac{2 \times 2 + 1}{2} \times 3 = \frac{1}{5} \times \frac{5}{2} \times 3 = \frac{1}{2} \times 3 = \frac{3}{2}$

5) $\displaystyle\\\rm\\\frac{12}{25} : \left(\frac{4}{5} : \frac{9}{35} \right) = \frac{12}{25} : \left(\frac{4}{5} \times \frac{35}{9} \right) = \frac{12}{25} : \frac{140}{45} = \frac{12}{25} \times \frac{45}{140} = \frac{540}{3500} = \frac{27}{175}$

6) $\displaystyle\\\rm\\\left(\frac{5}{2}:\frac{10}{7}\right):\frac{14}{3} = \left(\frac{5}{2} \times \frac{7}{10}\right) : \frac{14}{3} = \frac{35}{20} : \frac{14}{3} = \frac{35}{20} \times \frac{3}{4} = \frac{105}{80} = \frac{21}{16}$

7) $\displaystyle\\\rm\\40\% \ din \ 1600 = \frac{40}{100} \times 1600 = 40 \times 16 = 640$

8) $\displaystyle\\\rm\\75\% \ din \ 7000 = \frac{75}{100} \times 7000 = 75 \times 70 = 5250$

9) $\displaystyle\\\rm\\\frac{x}{36} = \frac{15}{12} \implies 15 \times 36 = 12 \times x \implies x = \frac{15\times 36}{12} = 15 \times 3= 45$

10) $\displaystyle\\\rm\\\frac{48}{x} = \frac{8}{7} \implies 8x = 48 \times 7 \implies x = \frac{48 \times 7}{8} = 6 \times 7 = 42$