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a) 5 : 3/4 - 4 4/5 : 3/4
= 5 . 4/3 - 24/5 . 4/3
= (5 - 24/5) . 4/3
= 1/5 × 4/3
= 4/15
b) -3/5 . 2/7 + (-3/7) . 3/5 + (-3/7)
= (-3/7) . (2/5 + 3/5 + 1)
= (-3/7) . 2
= -6/7
c) [(-4 2/7) . 7/11 + 7/11 . (5 1/3)] . 5 - 5 2/3
= (-30/7 . 7/11 + 7/11 . 16/3) . 5 - 17/3
= (-30/11 + 112/33) . 5 - 17/3
= 2/3 . 5 - 17/3
= 10/3 - 17/3
= -7/3
d) 5/39 . [(7 4/5) . (1 2/3) + (8 1/3) . (7 4/5)]
= 5/39 . (39/5 . 5/3 + 25/3 . 39/5)
= 5/39 . 39/5 . (5/3 + 25/3)
= 1 . 10
= 10
=
-99-(-98).(-97)>0
-5+(-4)+(-3)-(-2)-(-1)<0
Chúc bạn học tốt nha
$\textbf{Ta có:}$
$A=\dfrac{-5^2-5\cdot3^2}{5^3+5^2\cdot3^2}$
$=\dfrac{-25-45}{125+225}$
$=\dfrac{-70}{350}$
$=-\dfrac15.$
Và
$B=\dfrac{2^{12}\cdot3^{10}+6^9\cdot120}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}$
$=\dfrac{2^{12}3^{10}+2^{12}3^{10}\cdot5}{2^{11}3^{11}(2\cdot3-1)}$
$=\dfrac{2^{12}3^{10}(1+5)}{2^{11}3^{11}\cdot5}$
$=\dfrac{2^{12}3^{10}\cdot6}{2^{11}3^{11}\cdot5}$
$=\dfrac{2^2}{5}$
$=\dfrac45.$
=> $M=B-A$$=\dfrac45-\left(-\dfrac15\right)$
$=\dfrac55$$=1.$
a, 20^2 - 6^ 2= 400 - 36 = 364
b,3^3 . 18 - 3^3 . 12 = 3^3 . ( 18-12) = 27 . 6 = 162
c, 39 . 213 + 87 . 39 = ( 213 + 87) . 39 = 300 . 39 = 110700
d, 80 - [ 130 - ( 12 - 4)^2] = 80 - [130 - (3^2) ] = 80 - 130 - 9 = -59
Câu a:
2/3 + 1/5.10/7
= 2/3 + 2/7
= 14/21 + 6/21
= 20/21
Câu b:
2/7 + 5/7.14/25
= 2/7 + 2/5
= 10/35 + 14/25
= 24/35
Câu c:
7/12 - 27/7.1/18
= 7/12 - 3/14
= 49/84 - 18/84
= 31/84
Câu d:
3/10.(-5/6) - 1/8
= - 1/4 - 1/8
= -2/8 - 1/8
= - 3/8
\(\dfrac{5}{12}-\dfrac{3}{4}-\dfrac{5}{-3}\\ =\dfrac{5}{12}-\dfrac{3}{4}+\dfrac{5}{3}\\ =\dfrac{5}{12}-\dfrac{9}{12}+\dfrac{20}{12}\\ =\dfrac{5-9+20}{12}\\ =\dfrac{16}{12}\\ =\dfrac{4}{3}\)
5/12-3/4-5/-3
=5/12-9/12-(-20/12)
=5/12-9/12+20/12
=16/12=4/3