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1) 23 . 45 + 23 . 55 - 23
= 23 . (45 + 55 - 1)
= 23 . 99
= 2277
2) 2349 : 21 + {67 . 13 + [23 + 45 - (45 + 2)]}
= 2349 : 2 + {67 . 1 + [68 - (45 + 2)]}
= 1174,5 + {67 + [68 - 47]}
= 1174,5 + {67 + 21}
= 1174,5 + 88
= 1262,5
3) 23 + 3 . 9 + 56
= 23 + 27 + 56
= 50 + 56
= 106
1:
a: =7/5(40+1/4-25-1/4)-1/2021
=21-1/2021=42440/2021
b: =5/9*9-1*16/25=5-16/25=109/25
a, x+1/3=2/5-(-1/3)
<=>x+1/3=2/5+1/3
<=>x+1/3=11/15
<=>x=11/15-1/3
<=>x=2/5
Vậy x=2/5
b, 3/7-x=1/4-(-3/5)
<=> 3/7-x=1/4+3/5
<=> 3/7-x=17/20
<=> x=3/7-17/20
<=> x=-59/140
vậy x=-59/140
1: \(\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{1}{2}-\dfrac{4}{23}+\dfrac{16}{21}\)
\(=1+\dfrac{1}{2}\)
\(=\dfrac{3}{2}\)
2: \(\left(\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}\right)-\left(\dfrac{79}{67}-\dfrac{28}{41}\right)\)
\(=\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}-\dfrac{79}{67}+\dfrac{28}{41}\)
\(=\dfrac{1}{3}\)
x+1/3=2/5-(-1/3)
x+1/3=2/5+1/3
x=2/5+(1/3-1/3)
x=2/5
x+1/3=2/5-(-1/3)
x+1/3=2/5+1/3
x=2/5+(1/3-1/3)
x=1/3