Tính:
12 19 - 7 19
tính nhanh 5/12*-4/19+-7/12*4/19-15/19
Chuyển dấu '' - '' của -7/12 sang cho 4/19 thứ 2
=> -4/9 x ( 5/12 + 7/12 ) - 15/19
= -4/9 x 1 - 15/19
= -4/9 - 15/9
= -19/9
tính nhanh
7/11 . 8/19 + 7/19 . 3/11 - 12/19
\(\frac{7}{11}.\frac{8}{19}+\frac{7}{19}.\frac{3}{11}-\frac{12}{19}\)
\(=\frac{56}{209}+\frac{21}{209}-\frac{12}{19}\)
\(=\frac{7}{19}-\frac{12}{19}\)
\(=-\frac{5}{19}\)
kb vs tớ nha
và nhớ ủng hộ nữa đó
Tính hợp lý biểu thức \(\dfrac{12}{11}\) - \(\dfrac{-7}{19}\)+\(\dfrac{12}{19}\)
\(=\dfrac{12}{11}+1=\dfrac{23}{11}\)
7/13 . 5/19 + 7/19 . 8/13 + 12/19
Mọi người làm tính nhanh hộ mình nhé!!!!!Mình gấp lắm rồi!
\(\dfrac{7}{19}\).\(\dfrac{5}{19}\) + \(\dfrac{7}{19}\).\(\dfrac{8}{13}\) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\).( \(\dfrac{5}{13}+\dfrac{8}{13}\)) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\) . \(\dfrac{13}{13}\) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\) + \(\dfrac{12}{19}\)
= \(\dfrac{19}{19}\)
= 1
= 35/13.19 + 56/13.19 + 12.13/13.19
= 35/13.19 + 56/13.19 + 156/13.19
= 35/a + 56/a + 156/a
a = 13.19
a = 13(20 - 1)
a = 13.20 - 13.1
a = 260 - 13
a = 247
=> 35/a + 56/a + 156/a = 35/247 + 56/247 + 156/247 = 247/247 = 1
Đây nhé bạn :D
Tính hợp lí:
g) \(\dfrac{-3}{4}+\dfrac{2}{7}+\dfrac{-1}{4}+\dfrac{3}{5}+\dfrac{5}{7}\)
h) \(\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{19}.\dfrac{3}{11}-\dfrac{12}{19}\)
i) \(19\dfrac{5}{8}:\dfrac{7}{2013}-26\dfrac{5}{8}:\dfrac{7}{2013}\)
k) \(\dfrac{-5}{12}.\dfrac{2}{11}+\dfrac{-5}{12}.\dfrac{9}{11}+\dfrac{5}{12}\)
g: \(=\dfrac{-3}{4}-\dfrac{1}{4}+\dfrac{5}{7}+\dfrac{2}{7}+\dfrac{3}{5}=\dfrac{3}{5}\)
h: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{7}{19}-\dfrac{12}{19}=-\dfrac{5}{19}\)
i: \(=\dfrac{2013}{7}\left(19+\dfrac{5}{8}-26-\dfrac{5}{8}\right)=\dfrac{2013}{7}\cdot\left(-7\right)=-2013\)
tính hợp lí : 12/19 . 7/15 . -13/17 . 19/12 . 17/13
1) Tính nhanh
a) 7/19. 8/11 + 7/19.3/11 + 12/19
7/19 . 8/11 + 7/19 . 3/11 + 12/19
= 7/19 . ( 8/11 + 3/11 ) + 12/19
= 7/19 . 1 + 12/19
=7/19 + 12/19
= 1
Hi vọng các bạn nha
Bài 2: Thực hiện phép tính một cách hợp lí
f) \(\dfrac{7}{19}\) . \(\dfrac{8}{11}\) + \(\dfrac{3}{11}\) . \(\dfrac{7}{19}\) +\(\dfrac{-12}{19}\)
i) ( \(\dfrac{3}{8}\) + \(\dfrac{-3}{4}\)+ \(\dfrac{7}{12}\) ) : \(\dfrac{5}{6}\) +\(\dfrac{1}{2}\)
f: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{7}{19}-\dfrac{12}{19}=\dfrac{-5}{19}\)
i: \(=\left(\dfrac{9}{24}-\dfrac{18}{24}+\dfrac{14}{24}\right)\cdot\dfrac{6}{5}+\dfrac{1}{2}=\dfrac{5}{24}\cdot\dfrac{6}{5}+\dfrac{1}{2}\)
=1/4+1/2=3/4
` 7/19 . 8/11 + 3/11 . 7/19 + (-12)/19 `
`= 7/19 . ( 8/11 + 3/11 ) + (-12)/19 `
`= 7/19 . 11/11 + (-12)/19`
`= 7/19 . 1 + (-12)/19 `
`= 7/19 + (-12)/19 `
`= -5/19 `
`( 3/8 + (-3)/4 + 7/12 ) : 5/6 + 1/2`
`= 3/8 + (-3)4 + 7/12 . 6/5 + 1/2`
`= ( 9+(-18) + 14)/24 . 6/5 + 1/2`
`= 5/24 . 6/5 + 1/2`
`= 1/4 + 1/2 `
`= 3/4`
thực hiện phép tính
\(\frac{7}{19}.\frac{8}{11}+\frac{7}{19}.\frac{3}{11}+\frac{12}{19}\)
\(=\frac{7}{19}.\left(\frac{8}{11}+\frac{3}{11}\right)+\frac{12}{19}\)
\(=\frac{7}{19}.1+\frac{12}{19}\)
\(=1\)
\(\frac{7}{19}\).\(\frac{8}{11}\)+\(\frac{7}{19}\).\(\frac{3}{11}\)+\(\frac{12}{19}\)
=\(\frac{7}{19}\).1+\(\frac{12}{19}\)
=1
hok tốt
A=\(\dfrac{7}{19}\).\(\dfrac{8}{11}\) +\(\dfrac{7}{19}\).\(\dfrac{3}{11}\)+\(\dfrac{12}{19}\) Kết quả phép tính là? A.1 B.2 C.3 D.4