12+17=????????????????????????
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a) 12/17 : 17/12 + 5/7 : 17/12
= (12/17 + 5/7) : 17/12
= 1 : 17/12
= 12/17
Bài làm
Cách 1 :\(\frac{12}{17}:\frac{17}{12}+\frac{5}{7}:\frac{17}{12}\)
= \(\frac{12}{17}.\frac{12}{17}+\frac{5}{7}.\frac{12}{17}\)
= \(\frac{12}{17}.\left(\frac{12}{17}+\frac{5}{7}\right)\)
= \(\frac{12}{17}.\frac{169}{119}\)
= \(\frac{2028}{2023}\)
Cách 2 : \(\frac{12}{17}:\frac{17}{12}+\frac{5}{7}:\frac{17}{12}\)
= \(\frac{144}{289}+\frac{60}{119}\)
= \(\frac{2028}{2023}\)
2/5 + 3/4 = 23/40
7/12 - 2/7 + 1/12 = 25/84 + 1/12 = 8/21
12/17 - 5/17 - 4/17 = 3/17
OK
\(\frac{2}{5}+\frac{3}{4}=\frac{8}{20}+\frac{15}{20}=\frac{23}{20}\)
\(\frac{7}{12}-\frac{2}{7}+\frac{1}{12}=\left(\frac{7}{12}+\frac{1}{12}\right)-\frac{2}{7}=\frac{2}{3}-\frac{2}{7}=\frac{14}{21}-\frac{6}{21}=\frac{8}{21}\)
\(\frac{12}{17}-\frac{5}{17}-\frac{4}{17}=\frac{12-5-4}{17}=\frac{3}{17}\)
\(\dfrac{12}{17}.\dfrac{5}{7}-\left(-\dfrac{12}{17}\right).\dfrac{1}{7}+\dfrac{1}{17+7}\)
\(=\dfrac{12}{17}.\dfrac{5}{7}+\dfrac{12}{17}.\dfrac{1}{7}+\dfrac{1}{24}\)
\(=\dfrac{12}{17}\left(\dfrac{5}{7}+\dfrac{1}{7}\right)+\dfrac{1}{24}\)
\(=\dfrac{12}{17}.\dfrac{6}{7}+\dfrac{1}{24}\)
\(=\dfrac{72}{119}+\dfrac{1}{24}=\dfrac{1847}{2856}\)
a) 2/5+3/4=23/20
7/12-2/7+1/12=8//21
12/17-5/17-4/17=3/17
b) 675,39+342,14=1017,53
563,87+403,13-328,35=638,65
a) 2/5+3/4
=8/20+15/20
=21/20
7/12-2/7+1/12
=7/12+1/12-2/7
=1/4-2/7
=7/28-8/28
=-1/28
12/17-5/17-4/17
=12/17-9/17
=3/17
b) 675,39+342,14
= 1017,53
563,87+403,13-328,35
= 967-328,35
= 638,65
\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow x\left(\frac{1}{2}-\frac{2}{3}\right)=\frac{7}{12}\Rightarrow x\cdot\left(\frac{3}{6}-\frac{4}{6}\right)=\frac{7}{12}\)
\(\Rightarrow x\cdot\left(-1\right)=\frac{7}{12}\Rightarrow x=\frac{7}{12}:\left(-1\right)=\frac{7}{-12}\)
\(c,\frac{\left(x-5\right)}{12}\cdot\frac{9}{29}=\frac{-6}{29}\Rightarrow\frac{\left(x-5\right)}{12}=\frac{-6}{29}:\frac{9}{26}\)
\(\frac{\Rightarrow\left(x-5\right)}{12}=\frac{-6}{9}=\frac{-2}{3}\Rightarrow x-5=-\frac{2}{3}\cdot12\)
\(\Rightarrow x-5=\frac{-24}{3}=-8\Rightarrow x=-8+5=-3\)
\(a,0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\Rightarrow-\frac{1}{6}x=\frac{7}{12}\)
\(\Rightarrow x=-\frac{7}{2}\)
\(c,\frac{x-5}{12}\cdot\frac{9}{29}=-\frac{6}{29}\)
\(\Rightarrow\frac{x-5}{12}=-\frac{2}{3}\)
\(\Rightarrow x-5=12.\left(-\frac{2}{3}\right)\)
\(\Rightarrow x-5=-8\)
\(\Rightarrow x=-3\)
phép tính cứ làm bình thường nha nhân chia trước cộng trừ sau , cái gì trung đặt ra ngoài .xin lỗi vì vt hơ mỏi tay nên mik vt lời thôi nha
~ hok tốt ~
11/23 × 12/17+11/23×5/17+12/23
=(11/23+12/23) x (12/17+5/17)
=1 x 1
=1
11/23 × 12/17+11/23×5/17+12/23
=11/23 × 12/17+11/23×5/17+12/23x1
=11/23 × (12/17+5/17+1)
=11/23 × 2
= 22/23
Bài 1:
a: =25+75=100
b: =60-17-43+12=12
c: =-2-18=-20
d: =-3+36-17=36-20=16
Bài 2:
a: =-102
b: =-1000
c: =12x15=180
d: =21x(-10)=-210
TL
29
TK cho m
HT
12+17= 29. Vì đơn vị + đơn vị, hàng chục + hàng chục ( trường hợp đơn vị cộng với nhau không lớn hơn 10)