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\(\dfrac{16}{21}+\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}-\dfrac{5}{21}\)
\(=\left(\dfrac{16}{21}+\dfrac{5}{21}-\dfrac{5}{21}\right)+\left(\dfrac{4}{23}-\dfrac{4}{23}\right)\)
\(=\dfrac{16}{21}+0+0\)
\(=\dfrac{16}{21}\)
\(\dfrac{16}{21}+\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}-\dfrac{5}{21}\)
\(=\left(\dfrac{16}{21}+\dfrac{5}{21}-\dfrac{5}{21}\right)+\left(\dfrac{4}{23}-\dfrac{4}{23}\right)\)
\(=\left(\dfrac{16+5-5}{21}\right)+\left(\dfrac{4-4}{23}\right)\)
\(=\dfrac{16}{21}+0\)
\(=\dfrac{16}{21}\)
1, \(\frac{5}{21}+0,5-\frac{19}{23}+\frac{16}{21}-\frac{4}{23}\)
\(=\frac{5+16}{21}-\frac{19+4}{23}+0,5\)
\(=1-1+0,5\)
\(=0,5\)
2,\(\frac{27}{23}+\frac{5}{21}-\frac{4}{23}+\frac{6}{21}+\frac{1}{2}\)
\(=\frac{27-4}{23}+\frac{5+6}{21}+\frac{1}{2}\)
\(=1+\frac{11}{21}+\frac{1}{2}\)
\(=\frac{42+22+21}{42}\)
\(=\frac{85}{42}\)
a) Ta có:
C = 5/18 + 8/19 - 7/21 + (-10/36 + 11/19 + 1/3) - 5/8
C = 5/18 + 8/19 - 1/3 - 5/18 + 11/19 + 1/3 - 5/8
C = (5/18 - 5/18) + (8/19 + 11/19) - (1/3 - 1/3) - 5/8
C = 1 - 5/8
c = 3/8
b) F = 15/14 - (17/23 - 80/87 + 5/4) + (17/23 - 15/14 + 1/4)
F = 15/14 - 17/23 + 80/87 - 5/4 + 17/23 - 15/14 + 1/4
F = (15/14 - 15/14) - (17/23 - 17/23) + 80/87 - (5/4 - 1/4)
F = 80/87 - 1
F = -7/87
c) G = 1/25 - 4/27 + (-23/27 + -1/25 - 5/43) + 5/43 - 4/7
G = 1/25 - 4/27 - 23/27 - 1/25 - 5/43 + 5/43 - 4/7
G = (1/25 - 1/25) - (4/27 + 23/27) - (5/43 - 5/43) - 4/7
G = -1 - 4/7 = -11/7
27/23 + 5/21 - 4/23 + 0,5 + 16/21
= (27/23 - 4/23) + (5/12 + 16/21) + 0,5
= 1 + 1 + 0,5
= 2,5
27/23 + 5/21 - 4/23 + 0,5 + 16/21
= (27/23 - 4/23) + (5/12 + 16/21) + 0,5
= 1 + 1 + 0,5
= 2,5
Chúc bn học tốt!!!
( 27/23 - 4/23 ) + ( 5/21 + 6/21 ) + 1/2 = 1 + 11/21 +1/2 = 85/42
hình như bạn ghi có chút nhầm lẫn !
\(\dfrac{27}{23}+\dfrac{5}{21}-\dfrac{4}{23}+\dfrac{6}{21}-\dfrac{1}{2}\)
\(=\left(\dfrac{27}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{6}{21}\right)-\dfrac{1}{2}\)
\(=1+\dfrac{11}{21}-\dfrac{1}{2}\)
\(=\dfrac{32}{21}-\dfrac{1}{2}\)
\(=\dfrac{43}{42}\)