Tính nhanh:
21 x 19 + 19 x 79 / 38 x 50
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64x100+50x44
=2200+6400
=8600
1026+2774
=3800
mình làm đúng ko vậy
TL:
= 3800
nhé
K CHO MK NHAAAAAAA
BNNNNNNNNNNNNNNNNNNNNNNNNNN
~~HT~~
-79-79.99
=-79+(-79).99
=-79.100=-7900
19-42(-19)+38.5
=19.1+42.19+19.10
=19(1+42+10)
=19.53
=1007
a. 64 x 50 + 44 x 100
= 32 x 2 x 50 + 44 x 100
= 32 x 100 + 44 x 100
= (32 + 44) x 100
= 76 x 100
= 7600
b. 27 x 38 + 146 x 19
= 27 x 38 + 73 x 19 x 2
= 27 x 38 + 73 x 38
= (27 + 73) x 38
= 100 x 38
= 3800
a/b = 7600/3800 = 2
\(64\times50+44\times100\)
\(=32\times2\times50+44\times100\)
\(=\left(32+44\right)\times100\)
\(=76\times100=7600\)
b) -123.47 + 47.23 = -47(123 - 23) = -47.100 = -4700
\(x=\left(\dfrac{21}{19}-\dfrac{5}{19}\right)-\dfrac{24}{38}=\dfrac{4}{19}\)
3 x 15 + 21 x 15 + 85 x 5
= 45 + 315 + 425
= 785
15 - 30 + 40
= 25
21 + 19 - 50 + 10
= 0
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=-\dfrac{1}{20}+2\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{12}\times\dfrac{3}{12}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=-\dfrac{9}{20}\)
\(3\times15+21\times15+85\times5\\ =15\times\left(3+21\right)+425\\ =15\times24+425\\ =360+425\\ =785\)
\(15-30+40\\ =\left(15+40\right)-30\\ =55-30\\ =25\)
\(21+19-50+10\\ =\left(21+19\right)-\left(50-10\right)\\ =40-40\\ =0\)
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=\dfrac{4}{20}-\dfrac{5}{20}+\dfrac{40}{20}\)
\(=\dfrac{\left(4+40\right)}{20}-\dfrac{5}{20}\)
\(=\dfrac{44}{20}-\dfrac{5}{20}\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=\dfrac{2}{20}+\dfrac{4}{20}-\dfrac{15}{20}\)
\(=\dfrac{6}{20}-\dfrac{15}{20}\)
\(=-\dfrac{9}{20}\)
\(\frac{21.19+19.79}{38.50}\)
\(=\frac{19.\left(21+79\right)}{38.50}\)
\(=\frac{19.100}{38.50}\)
\(=\frac{19.2.50}{19.2.50}\)
\(=1\)
21 × 19 + 19 × 79 / 38 × 50
= 21 × 19 + 0,79
= ( 20 + 1 ) × 19 + 0,79
= 20 × 19 + 1 × 19 + 0,79
= 380 + 19 + 0,79
= 399 + 0,79
= 399,79