tính nhanh : a, 31/17 +-5/13+-8/13-14/17 b, -5/7.2/11+-5/7.9/11+5/7 18/10/2021 Bởi Abigail tính nhanh : a, 31/17 +-5/13+-8/13-14/17 b, -5/7.2/11+-5/7.9/11+5/7
$\text{ a) }$ $\text{ $\frac{31}{17}$ + $\frac{-5}{13}$ + $\frac{-8}{13}$ – $\frac{14}{17}$ }$ $\text{ = ($\frac{31}{17}$ – $\frac{14}{17}$) + ($\frac{-5}{13}$ + $\frac{-8}{13}$) }$ $\text{ = 1 + -1 }$ $\text{ = 0 }$ $\text{ b) }$ $\text{ $\frac{-5}{7}$ × $\frac{2}{11}$ + $\frac{-5}{7}$ × $\frac{9}{11}$ + $\frac{5}{7}$ }$ $\text{ = $\frac{-5}{7}$ × $\frac{2}{11}$ + $\frac{-5}{7}$ × $\frac{9}{11}$ + $\frac{5}{7}$ × -1 }$ $\text{ = [$\frac{2}{11}$ + $\frac{9}{11}$ + (-1)] × $\frac{-5}{7}$ }$ $\text{ = 0 × $\frac{-5}{7}$ }$ $\text{ = 0 }$ Bình luận
`a, 31/17 +{-5}/13+{-8}/13-14/17` `=(31/17-14/17) +({-5}/13+{-8}/13)` `=17/17+{-13}/13` `=1+(-1)` `=0` `b,{-5}/7 . 2/11+{-5}/7 . 9/11+5/7` `={-5}/7 . (2/11+9/11)+5/7` `={-5}/7 . 11/11+5/7` `={-5}/7 . 1+5/7` `={-5}/7+5/7` `={0}/7=0` Bình luận
$\text{ a) }$
$\text{ $\frac{31}{17}$ + $\frac{-5}{13}$ + $\frac{-8}{13}$ – $\frac{14}{17}$ }$
$\text{ = ($\frac{31}{17}$ – $\frac{14}{17}$) + ($\frac{-5}{13}$ + $\frac{-8}{13}$) }$
$\text{ = 1 + -1 }$
$\text{ = 0 }$
$\text{ b) }$
$\text{ $\frac{-5}{7}$ × $\frac{2}{11}$ + $\frac{-5}{7}$ × $\frac{9}{11}$ + $\frac{5}{7}$ }$
$\text{ = $\frac{-5}{7}$ × $\frac{2}{11}$ + $\frac{-5}{7}$ × $\frac{9}{11}$ + $\frac{5}{7}$ × -1 }$
$\text{ = [$\frac{2}{11}$ + $\frac{9}{11}$ + (-1)] × $\frac{-5}{7}$ }$
$\text{ = 0 × $\frac{-5}{7}$ }$
$\text{ = 0 }$
`a, 31/17 +{-5}/13+{-8}/13-14/17`
`=(31/17-14/17) +({-5}/13+{-8}/13)`
`=17/17+{-13}/13`
`=1+(-1)`
`=0`
`b,{-5}/7 . 2/11+{-5}/7 . 9/11+5/7`
`={-5}/7 . (2/11+9/11)+5/7`
`={-5}/7 . 11/11+5/7`
`={-5}/7 . 1+5/7`
`={-5}/7+5/7`
`={0}/7=0`