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a. 12x5+12x95=12x(5+95)=12x100=1200
b. 10x20x5x10=(10x10)x(20x5)=100x100=10000
tk nha
a, 12.5+12.95=12.(5+95)
=12.100
=1200
b,10.20.5.10=(10.10).(20.5)
=100.100
=10000
\(-\dfrac{5}{7}+\dfrac{8}{11}+\left(-\dfrac{2}{7}\right)+\dfrac{1}{4}+\dfrac{3}{11}.\\ =\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{1}{4}.\\ =-\dfrac{7}{7}+\dfrac{11}{11}+\dfrac{1}{4}.\\ =-1+1+\dfrac{1}{4}.\\ =0+\dfrac{1}{4}=\dfrac{1}{4}.\)
\(\dfrac{2}{7}.\dfrac{5}{13}+\dfrac{2}{7}\dfrac{6}{13}-\dfrac{2}{7}.1\dfrac{11}{13}.\\ =\dfrac{2}{7}.\dfrac{5}{13}+\dfrac{2}{7}\dfrac{6}{13}-\dfrac{2}{7}.\dfrac{24}{13}.\\ =\dfrac{2}{7}\left(\dfrac{5}{13}+\dfrac{6}{13}-\dfrac{24}{13}\right).\\ =\dfrac{2}{7}.\left(\dfrac{-13}{13}\right).\\ =\dfrac{2}{7}.\left(-1\right)=\dfrac{-2}{7}.\)
a) A = 37. 173 +62. 173 + 173
= 173. (37 +62 + 1)
= 173.100
= 17 300
b) B = 72.99 + 28.99 - 900
= 99. (72+28) - 900
= 99.100 - 900
= 9 900 - 900
= 9 000
c) C = 23.3-(110 + 15): 42
= 8.3 - (1 + 15): 42
= 8.3 - 16:42
= 8.3 - 1
= 23.
d) D = 62: 4.3 + 2.52 - 2010
= 36:4.3 + 2.25 - 1
= 27 + 50 - 1
= 76.
a) \(\left( {\frac{7}{3} + 3,5} \right):\left( { - \frac{{25}}{6} + \frac{{22}}{7}} \right) + 0,5\)
\(\begin{array}{l} = \left( {\frac{7}{3} + \frac{7}{2}} \right):\left( { - \frac{{25}}{6} + \frac{{22}}{7}} \right) + \frac{1}{2}\\ = \frac{{35}}{6}:\frac{{ - 25.7 + 22.6}}{{6.7}} + \frac{1}{2}\\ = \frac{{35}}{6}:\frac{{ - 43}}{{7.6}} + \frac{1}{2} = \frac{{35}}{6}.\frac{{7.6}}{{ - 43}} + \frac{1}{2}\\ = \frac{{ - 245}}{{43}} + \frac{1}{2} = \frac{{ - 245.2 + 43}}{{43.2}} = \frac{{ - 447}}{{86}}\end{array}\)
b) \(\frac{{38}}{7} + \left( { - 3,25} \right) - \frac{{17}}{7} + 4,55\)
\(\begin{array}{l} = \left( {\frac{{38}}{7} - \frac{{17}}{7}} \right) + \left( {4,55 - 3,25} \right)\\ = \frac{{38 - 17}}{7} + 1,3 = \frac{{21}}{7} +1,3\\ = 3 + 1,3 = 4,3\end{array}\)
a: =9,79-8,45=1,34
b: =-12,7+4,5=-8,2
a) 9,79 + (-8,45)
= 1.34
b) -12,7 - (-4,5)
= -12,7 + 4,5
= -8.2