Question

Calculați scazand factor comun fractiile:
a) 13/15-1/2-5/6×1/2

b)5/9 × 3/4 + 3/4 × 5/6 - 1/3×3/4

c)5/7 × 3/7 + 5/7 × 5/21 - 5/7 × 2/35

d)4/45 × 8/9 - 4/45 × 3/18 + 4/45 + 11/24 - 4/45 × 1/36
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Answer 1

Răspuns:

a) 13/15- 1/2x(1- 5/6)=$\frac{13}{15}$ - $\frac{1}{2}$ x$\frac{(6-5)}{6}$= $\frac{13}{15}$- $\frac{1}{2}$x$\frac{1}{6}$=$\frac{13}{15}$ -$\frac{1}{12}$ =$\frac{52-5}{60}$=$\frac{47}{60}$

b) $\frac{3}{4}$x ($\frac{5}{9}$+ $\frac{5}{6}$- $\frac{1}{3}$)=$\frac{3}{4}$ x $\frac{(10+15-6)}{18}$=$\frac{3}{4}$x $\frac{19}{18}$= $\frac{19}{24}$   (se aduce la acelasi numitor, se simplifica cu 3)

c) $\frac{5}{7}$ x( $\frac{3}{7}$+ $\frac{5}{21}$- $\frac{2}{35}$)= $\frac{5}{7}$x$\frac{1}{7}$ x( 3+ $\frac{5}{3}$-$\frac{2}{5}$) = $\frac{5}{49}$x$\frac{40-6}{15}$= $\frac{36}{3x49}$= $\frac{12}{49}$