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\(=5+5+...+5\)
Tổng trên có \(\left[\left(57-2\right):5+1\right]:2=6\left(\text{số 5}\right)\)
Vậy tổng là \(6\cdot5=30\)
\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{4}{13}\).\(\frac{-3}{5}\)+\(\frac{12}{7}\)=\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{-4}{13}\).\(\frac{3}{5}\)+\(\frac{12}{7}\)
=\(\frac{3}{5}\).(\(\frac{-9}{13}\)+\(\frac{-4}{13}\))+\(\frac{12}{7}\)
= \(\frac{3}{5}\).-1+\(\frac{12}{7}\)
=\(\frac{-3}{5}\)+\(\frac{12}{7}\)
=\(\frac{39}{35}\)
a)x+13=32-76
x+13=(-44)
x=-31
b)(-15)+x=43
x=43+15
x=58
c)8-(3-7)
=8+4
=12
d)(-5)-(9-12)
=(-5)+3
=-2
t tôi nha
1)
a) x + 13 = 32 - 76
x + 13 = -44
x = ( -44 ) - 13
x = -57
b) ( -15 ) + x = ( -14 ) - ( -57 )
( -15 ) + x = 43
x = 43 - ( -15 )
x = 58
2)
a) 8 - ( 3 - 7 ) = 8 - ( -4 ) = 12
b) ( -5 ) - ( 9 - 12 ) = ( -5 ) - ( -3 ) = -2
\(\frac{x-12}{3}=\frac{x+1}{4}\)
=>(x-12).4=(x+1)*3
4x-48=3x+3
4x-3x=48+3
x=51
(x-12)/3=(x+1)/4
(x-12)*4=(x+1)*3
x*4-12*4=x*3+1*3
4x-48=3x+3
4x-3x=3+48
x=51
\(\dfrac{7}{19}\).\(\dfrac{5}{19}\) + \(\dfrac{7}{19}\).\(\dfrac{8}{13}\) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\).( \(\dfrac{5}{13}+\dfrac{8}{13}\)) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\) . \(\dfrac{13}{13}\) + \(\dfrac{12}{19}\)
= \(\dfrac{7}{19}\) + \(\dfrac{12}{19}\)
= \(\dfrac{19}{19}\)
= 1
\(A=49\frac{8}{23}-\left(5\frac{7}{32}+14\frac{8}{23}\right)\)
\(A=49\frac{8}{23}-5\frac{7}{32}+14\frac{8}{23}\)
\(A= \left(49\frac{8}{23}-14\frac{8}{23}\right)-5\frac{7}{32}\)
\(A=\left[\left(49-14\right)-\left(\frac{8}{23}-\frac{8}{23}\right)\right]-5\frac{7}{32}\)
\(A=\left[35-0\right]-5\frac{7}{32}\)
\(A=35-5\frac{7}{32}\)
\(A=\frac{953}{32}\)
\(B=71\frac{38}{45}-\left(43\frac{38}{45}-1\frac{17}{57}\right)\)
\(B=71\frac{38}{45}-\frac{36377}{855}\)
\(B=\frac{1670}{57}\)
\(C=\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right):\frac{4}{5}\)
\(C=\left[\left(19\frac{5}{8}-13\frac{1}{4}\right):\frac{7}{12}\right]:\frac{4}{5}\)
\(C=\left[\frac{51}{8}:\frac{7}{12}\right]:\frac{4}{5}\)
\(C=\frac{153}{14}:\frac{4}{5}\)
\(C=\frac{765}{56}\)
\(D=\left[\left(\frac{10}{15}-\frac{2}{3}\right):\frac{1}{7}\right]\cdot0,15-\frac{1}{4}\)
\(D=\left[0:\frac{1}{7}\right]\cdot\frac{3}{20}-\frac{1}{4}\)
\(D=0\cdot\frac{3}{20}-\frac{1}{4}\)
\(D=0-\frac{1}{4}\)
\(D=-\frac{1}{4}\)
\(E=\frac{13}{30}+\frac{28}{45}\cdot2\frac{1}{2}-\left[\left(\frac{1}{2}+\frac{1}{3}\right):\frac{53}{90}\right]:\frac{50}{53}\)
\(E=\frac{13}{30}+\frac{28}{45}\cdot\frac{5}{2}-\left[\frac{5}{6}:\frac{53}{90}\right]:\frac{50}{53}\)
\(E=\frac{13}{30}+\frac{28}{45}\cdot\frac{5}{2}-\frac{75}{53}:\frac{50}{53}\)
\(E=\frac{13}{30}+\frac{14}{9}-\frac{3}{2}\)
\(\)\(E=\frac{22}{45}\)
CHUC BAN HOC TOT >.<
3/2-5/6+7/12-9/20+11/30-13/42+15/56-17/72
=1.5-0.8(3)+0.58(3)-0.3(6)-0.3(095238)+0.267(857142)-0236(1)
=0.(8)
tính nhanh nha bn thế là chưa tinh nhanh đâu
\(\dfrac{\left(12:13\right)+\left(12:131\right)-\left(12:1313\right)+\left(12:13131\right)}{\left(15:13\right)+\left(15:131\right)-\left(15:1313\right)+\left(15:13131\right)}\\ =\dfrac{12:\left(13+131-1313+13131\right)}{15:\left(13+131-1313+13131\right)}=\dfrac{12}{15}=\dfrac{4}{5}\)
(x-1).12^12=12^13
x-1=12^13:12^12
x-1=12
x=12+1
x=13
-HT-
\((x-1).12^{12}=12^{13}\)
\(\Leftrightarrow x-1=12^{13}:12^{12}\)
\(\Leftrightarrow x-1=12\)
\(\Leftrightarrow x=12+1\)
\(\Leftrightarrow x=13\)
\(V\text{ậy}x=13\)