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a) \(\dfrac{7}{-25}+\dfrac{8}{25}=\dfrac{-7}{25}+\dfrac{8}{25}=\dfrac{1}{25}\)
\(\dfrac{4}{5}+\dfrac{4}{-18}=\dfrac{4}{5+\left(-18\right)}=\dfrac{4}{-13}=\dfrac{-4}{13}\)
\(\dfrac{7}{21}+\dfrac{9}{-36}=\dfrac{1}{3}+\dfrac{1}{-4}=\dfrac{1}{3+\left(-4\right)}=\dfrac{1}{-1}=1\)
b) \(\dfrac{12}{20}-\dfrac{2}{5}=\dfrac{12}{20}+\left(\dfrac{-2}{5}\right)=\dfrac{3}{5}+\dfrac{-2}{5}=\dfrac{3+\left(-2\right)}{5}=\dfrac{1}{5}\)
\(\dfrac{2}{3}-\dfrac{-5}{6}=\dfrac{2}{3}+\dfrac{5}{6}=\dfrac{4}{6}+\dfrac{5}{6}=\dfrac{9}{6}=\dfrac{3}{2}\)
\(6-\dfrac{3}{20}=6+\dfrac{-3}{20}=\dfrac{60}{60}+\dfrac{-9}{60}=\dfrac{51}{60}\)
c) \(\dfrac{2}{21}.\dfrac{-7}{3}=\dfrac{2.\left(-1\right)}{7.3}=\dfrac{-2}{21}\)
\(\dfrac{27}{28}.\left(-21\right)=\dfrac{27.\left(-21\right)}{28}=\dfrac{-567}{28}\)
\(\dfrac{-15}{7}.\dfrac{-14}{25}=\dfrac{-3.\left(-2\right)}{1.5}=\dfrac{6}{5}\)
a) \(...=16.\left(36-37\right)=16.\left(-1\right)=-16\)
b) \(...=9.3+9.50=9.\left(3+50\right)=9.53=477\)
c) \(...=2.\left(\left(5.16-18\right)+36:18\right)=2.\left(70+2\right)=2.72=144\)
d) \(...=5\left(48:8+44\right)=5\left(6+44\right)=5.50=250\)
e) \(...=20-6=14\)
f) \(...=50+13-2=61\)
a) 16 . 36 - 16 . 37
= 16 . (36 - 37)
= 16 . (-1)
= -16
b) 36 : 4 . 3 + 9 . 50
= 9 . 3 + 9 . 50
= 9 . (3 + 50)
= 9 . 53
= 477
c) 2 . (5 . 16 - 18) + 36 : 18 . 2
= 2 . (80 - 18) + 2 . 2
= 2 . 62 + 2 . 2
= 2 . (62 + 2)
= 2 . 64
= 128
Tham khảo :
(Tại mik lười ko mún ghi nên bạn tham khảo cái ảnh này nhá)
a)
\(\dfrac{1}{2}=0,5;\dfrac{3}{4}=0,75;\dfrac{7}{5}=1,4;\dfrac{9}{8}=1,125;\dfrac{26}{25}=1,04;\dfrac{120}{125}=0,96\)
b)
\(\dfrac{15}{25}=0,6;\dfrac{75}{25}=3;\dfrac{90}{300}=0,3;\dfrac{27}{36}=0,75;\dfrac{51}{85}=0,6\)
a,1/2=5/10;3/4=75/100;7/5=140/100;26/25=108/100;120/125=960/1000
b,15/25=60/100;75/25=300/100;90/300=3/10;27/36=3/4=75/100;
51/85=3/5=60/100;39/65=3/5=60/100
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
2/25=.2../25 .27../36=3/4
3/.12..=9/36
15/27=5/..9..
..20..28=5/7
36/72=..1../2
\(\dfrac{2}{25}=\dfrac{2}{25}\)
\(\dfrac{27}{36}=\dfrac{3}{4}\)
\(\dfrac{3}{12}=\dfrac{9}{36}\)
\(\dfrac{15}{27}=\dfrac{5}{9}\)
\(\dfrac{20}{28}=\dfrac{5}{7}\)
\(\dfrac{36}{72}=\dfrac{1}{2}\)