7/5+8/25
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A=2/7+-3/8+11/7+1/3+1/7+5/-8
A=(2/7 + 1/7 + 11/7) + (-3/8 + 5/-8) + 1/3
A=2 + (-1) + 1/3
A=1 + 1/3
A=4/3
B=-3/8+12/25+5/-8+2/-5+13/25
B=(-3/8 + 5/-8) + (12/25 + 13/25) + 2/-5
B=-1 + 1 + 2/-5
B=-2/5
\(A=\left(\dfrac{2}{7}+\dfrac{11}{7}+\dfrac{1}{7}\right)+\left(\dfrac{-3}{8}+\dfrac{-5}{8}\right)+\dfrac{1}{3}=2-1+\dfrac{1}{3}=1+\dfrac{1}{3}=\dfrac{4}{3}\)
\(B=\dfrac{-3}{8}+\dfrac{12}{25}+\dfrac{-5}{8}+\dfrac{-2}{5}+\dfrac{13}{25}=1+1-\dfrac{5}{8}=-\dfrac{5}{8}\)
`@` `\text {Ans}`
`\downarrow`
`1,`
`a)`
`-7/25 + (-8)/25`
`= (-7 - 8)/25`
`= -15/25`
`= -3/5`
`b)`
`6/13 + (-15)/39`
`= 18/39 + (-15)/39`
`= (18 - 15)/39`
`= 3/39`
`= 1/13`
`c)`
`5/7 + 4/(-14)`
`= 10/14 + (-4)/14`
`= (10 - 4)/14`
`= 6/14`
`= 3/7`
`d)`
`-8/18 + (-15)/27`
`= -4/9 + (-5)/9`
`= (-4-5)/9`
`= -9/9 = -1`
`2,`
`a)`
`3/5 + (-7)/4`
`= 12/20 + (-35)/20`
`= (12 - 35)/20`
`=-23/20`
`b)`
`(-2) + (-5)/8`
`= (-16)/8 + (-5)/8`
`= (-16 - 5)/8`
`= -21/8`
`c)`
`1/8 + (-5)/9`
`= 9/72 + (-40)/72`
`= (9-40)/72`
`= -31/72`
`d)`
`6/13 + (-14)/39`
`= 18/39 + (-14)/39`
`= (18 - 14)/39`
`= 4/39`
`e)`
`(-18)/24 + 15/21`
`= (-3)/4 + 5/7`
`= (-21)/28 + 20/28`
`= (-21 + 20)/28`
`= -1/28`
= 1, 72 nha bn
7/5 + 8/25
= 35/25 + 8/25
= 43/25