Question

Calculati a)14/15-2/15+17/20-7/20==b)5/7-3/7+3/14+5/14=; ;c)8/15×(15/16÷3/8×3/4)=;d)9/10÷[(3 5/8-1 3/8)÷2]=

Answer 1

a) 14/15-2/15+17/20-7/20=

=(14-2)/15+(17-7)/20=

=12/15+10/20=

=12/15+1/2=

(amplific fracțiile cu 2, respectiv 15)

=24/30+15/30=(24+15)/30=39/30=13/10

b) 5/7-3/7+3/14+5/14=

=(5-3)/7+(3+5)/14=

=2/7+8/14=

(amplific prima fractie cu 2)

=4/14+8/14=(4+8)/14=12/14=6/7

c) 8/15x(15/16:3/8x3/4)=

=8/15x(15/16x8/3x3/4)=

(din fracțiile 15/16 și 8/3, 15 se reduce cu 3, iar 16 se reduce cu 8)

=8/15x(5/2x1/1x3/4)=

=8/15x5/2x3/4=

(din fracțiile 8/15 și 5/2, 8 se reduce cu 2, iar 15 cu 5)

=4/3x1/1x3/4=4/3x3/4=1

d) 9/10:[(3 5/8-1 3/8):2]=

=9/10:[(29/8-11/8):2]=

=9/10:(18/8:2)=

=9/10:(18/8x1/2)=

=9/10:9/8=9/10x8/9=10/8=5/4