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a; \(\dfrac{9}{27}\) + \(\dfrac{7}{-49}\)
= \(\dfrac{1}{3}\) - \(\dfrac{1}{7}\)
= \(\dfrac{7}{21}\) - \(\dfrac{3}{21}\)
= \(\dfrac{4}{21}\)
b; - \(\dfrac{12}{10}\) + \(\dfrac{-25}{30}\)
= - \(\dfrac{6}{5}\) - \(\dfrac{5}{6}\)
= -\(\dfrac{36}{30}\) - \(\dfrac{25}{30}\)
= \(\dfrac{-61}{30}\)
c; \(\dfrac{-20}{35}\) + \(\dfrac{-16}{-24}\)
= - \(\dfrac{4}{7}\) + \(\dfrac{2}{3}\)
= - \(\dfrac{12}{21}\) + \(\dfrac{14}{21}\)
= \(\dfrac{2}{21}\)
d; - \(\dfrac{21}{77}\) + \(\dfrac{10}{-35}\)
= - \(\dfrac{3}{11}\) - \(\dfrac{2}{7}\)
= - \(\dfrac{21}{77}\) - \(\dfrac{22}{77}\)
= - \(\dfrac{43}{77}\)
a)27^6:9^3=(3^3)^6:(3^2)^3=3^18:3^6=3^12
b)4^20:2^15=(2^2)^20:2^15=2^40:2^15=2^25
a) 27^6 : 9^3
= ( 3^3)^6 : ( 3^2)^3
= 3^18 : 3^6
= 3^12
b) 4^20 : 2^15
= ( 2^2)^20 : 2^15
= 2^40 : 2^15
= 2^25
d) 64^4 x 16^5 : 4^20
= (4^3)^4 x (4^2)^5 : 4^20
= 4^12 x 4^10 : 4^20
= 4^22 : 4^20
= 4^2
a, \(7^{2010}:7=7^{2009}\)
b, \(4^{20}:4^0=4^{20}\)
c, \(\frac{3^8.3^{15}}{3^7.3^{14}}=\frac{3^{23}}{3^{21}}=3^2\)
d, \(\frac{4^{16}.4^2}{4^{20}:4^2}=\frac{4^{18}}{4^{18}}=4^0\)
e, \(\frac{2^{15}:2^{10}}{2^{18}:2^{15}}=\frac{2^5}{2^3}=2^2\)
f, \(25^4:125=\left(5^2\right)^4:5^3=5^8:5^3=5^5\)
a) 19915 . 19925 = 19915 + 25 = 19940
b) 352019 : 352012 = 352019 - 2012 = 357
c) a . a99 = a1 + 99 = a100
d) x : x15 . x6 = x1 - 15 . x6 = x-14 . x6 = x-14 + 6 = x-8
e) 16 . 25 = (24)1 . 25 = 24 . 25 = 24 + 5 = 29
g) 49 . 75 = 72 . 75 = 72 + 5 = 77
h) 36 . 216 = (bí r!)
k) a2019 : a2015 = a2019 - 2015 = a4