Question

din fiecare dintre sirurile de fractii de mai jos gasiti fractiile echivalente: a) 3 supra 7, 5 supra 4, 21 supra 9, 1 supra 2, 5 supra 10, 9 supra 21, 10 supra 8, 40 supra 80. va rog ziceti toate optiunile. dau coroana

Answer 1

Răspuns:

doua fractii a/b și c/d sunt echivalente dacă a·d=b·c

3/7=9/21 → fractii echivalente

3·21=7·9

63=63

5/4=10/8

5·8=10/4

40=40

1/2=5/10

1·10=2·5

10=10

5/10=40/80

5·80=10·40

400=400

1/2=40/80

1·80=40·2

80=80

Answer 2

$\mathbf{Dou\check{a} \: fractii\;\: \dfrac{a}{b} \:si\:\dfrac{c}{d}\:sunt\:echivalente\:daca\:produsul\:meziilor\:si\:al\:extremilor\:este\:egal. }$

$\mathbf{\dfrac{a}{b}=\dfrac{c}{d} \implies \boxed{\mathbf{a \cdot d = b \cdot c}} }$

$\mathbf{a\:si\:d - extremii\: | \: b\:si\:c -mezii}$

$\mathbf{3 \cdot 21 = 7\cdot 9 \implies \dfrac{3}{9}=\dfrac{7}{21} }$

$\mathbf{5 \cdot 8 = 4 \cdot 10 \implies \dfrac{5}{10}=\dfrac{4}{8} }$

$\mathbf{1\cdot 10 = 5 \cdot 2 \implies \dfrac{1}{5} =\dfrac{2}{10} }$

$\mathbf{5\cdot 80 = 40 \cdot 10 \implies \dfrac{80}{40} =\dfrac{10}{5} }$

$\mathbf{80\cdot 1 = 40 \cdot 2 \implies \dfrac{1}{40} =\dfrac{2}{80} }$