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Đ=(12/6+7/8)-(-7/8+12/6)
Bỏ ngoặc
\(Đ=\frac{12}{6}+\frac{7}{8}+\frac{7}{8}-\frac{12}{6}\)
\(Đ=\left(\frac{12}{6}-\frac{12}{6}\right)+\left(\frac{7}{8}+\frac{7}{8}\right)\)
\(Đ=0+\frac{7}{4}\)
\(Đ=\frac{7}{4}\)
Cách 1: = ( 36/6 - 4/6 + 3/6 ) - ( 30/6 + 10/6 - 9/6 ) - ( 18/6 - 14/6 + 15/6 )
= 35/6 - 31/6 - 19/6
= -5/2
Cách 2: = 6 - 2/3 + 1/2 - 5 - 5/3 + 3/2 -3 + 7/3 - 5/2
= ( 6 - 5 - 3 ) + ( -2/3 - 5/3 + 7/3 ) + ( 1/2 + 3/2 - 5/2 )
= -2 + 0 + -1/2
= -5/2
C1: \(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(A=\left(5\frac{1}{3}+\frac{1}{2}\right)-\left(6\frac{2}{3}-\frac{3}{2}\right)-\left(\frac{2}{3}+\frac{5}{2}\right)\)
\(A=5\frac{5}{6}-5\frac{1}{6}-3\frac{1}{6}\)
\(A=-2\frac{1}{2}\)
C2: \(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(A=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(A=\left(6-5-3\right)-\left(\frac{2}{3}+\frac{5}{3}-\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(A=-2+\left(-\frac{1}{2}\right)=-2\frac{1}{2}\)
Cách 2:
\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=\left(\frac{36}{6}-\frac{4}{6}+\frac{3}{6}\right)-\left(\frac{30}{6}+\frac{10}{6}-\frac{9}{6}\right)-\left(\frac{18}{6}-\frac{14}{6}+\frac{15}{6}\right)\)
\(=\frac{36}{6}-\frac{4}{6}+\frac{3}{6}-\frac{30}{6}-\frac{10}{6}+\frac{9}{6}-\frac{18}{6}+\frac{14}{6}-\frac{15}{6}\)
\(=\frac{36-4+3-30-10+9-18+14-15}{6}\)
\(=-\frac{15}{6}=-\frac{5}{2}\)
Bài 1:
a, \(\dfrac{-x-2}{3}\) = - \(\dfrac{6}{7}\)
- \(x\) - 2 = - \(\dfrac{18}{7}\)
\(x\) = - 2 + \(\dfrac{18}{7}\)
\(x\) = - \(\dfrac{4}{7}\)
Bài b, \(\dfrac{4}{7-x}\) = \(\dfrac{1}{3}\)
12 = 7 - \(x\)
\(x\) = 7 - 12
\(x\) = -5
***** nhá, mất công làm đấy
C1:
\(A=\left(\frac{36}{6}-\frac{4}{6}+\frac{3}{6}\right)-\left(\frac{150}{30}+\frac{50}{30}+\frac{45}{30}\right)-\left(\frac{18}{6}-\frac{14}{6}+\frac{15}{6}\right)\)
\(=\frac{35}{6}-\frac{155}{30}-\frac{19}{6}=\frac{35}{6}-\frac{19}{6}-\frac{155}{30}\)
\(=\frac{16}{6}-\frac{155}{30}=\frac{80}{30}-\frac{155}{30}=\frac{75}{30}=\frac{-5}{2}=-2\frac{1}{2}\)
C2:
\(A=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=\left(6-5-3\right)-\left(\frac{2}{3}+\frac{5}{3}-\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(=-2-0+\frac{-1}{2}\)
\(=-2+\frac{-1}{2}=-2\frac{1}{2}\)
Thực hiện phép tính sau:
\(B=\frac{5}{9}.2,\left(37\right)+0,\left(5\right).3,\left(62\right)-2\sqrt{\left(\frac{-2}{3}\right)^2}\)
\(A=\left(37,1-4,5\right)-\left(-4,5+37,1\right)\)
\(=37,1-4,5+4,5-37,1\)
\(=37,1-37,1-4,5+4,5\)
\(=0.\)
\(B=-\left(315.4+275\right)+4.315-\left(10-275\right)\)
\(=-315.4-275+4.315-10+275\)
\(=-315.5+4.315-275+275-10\)
\(=0+0-10=-10.\)
\(C=-\left(\frac{3}{7}+\frac{3}{8}\right)-\left(-\frac{3}{8}+\frac{4}{7}\right)\)
\(=-\frac{3}{7}-\frac{3}{8}+\frac{3}{8}-\frac{4}{7}\)
\(=-\frac{3}{7}-\frac{4}{7}-\frac{3}{8}+\frac{3}{8}\)
\(=-1+0=-1.\)
A=37,1 - 4,5 + 4,5 - 37,1
A=(37,1 - 37,10) + ( 4,5 - 4,5 )
A = 0 + 0 = 0
B= -315.4 - 275 + 4.315 - 10 + 275
B=(-315.4 + 4.315) + ( 275-275) - 10
B= 0 + 0 - 10 = -10
C= -3/7 - 3/8 + 3/8 - 4/7
C = ( -3/7-4/7) + ( 3/8 - 3/8)
C=-7/7 + 0 = -7/7 = -1
Cách 1: Tính giá trị từng biểu thức trong ngoặc
A=
Cách 2: Bỏ dấu ngoặc rồi nhóm các số hạng thích hợp
A =
= (6-5-3) -
= -2 -0 - = - (2 + ) = -2
Lời giải:
Cách 1: Tính giá trị từng biểu thức trong ngoặc
A=
Cách 2: Bỏ dấu ngoặc rồi nhóm các số hạng thích hợp
A =
= (6-5-3) -
= -2 -0 - = - (2 + ) = -2
=\(\frac{-3}{7}+\frac{3}{8}-\frac{3}{8}-\frac{4}{7}\)
= \(\frac{-3}{7}-\frac{4}{7}=\frac{-7}{7}=-1\)
\(-\left(\frac{3}{7}+\frac{3}{8}\right)-\left(-\frac{3}{8}+\frac{4}{7}\right)\)
\(=\frac{-3}{7}-\frac{3}{8}+\frac{3}{8}-\frac{4}{7}\)
\(=\left(\frac{-3}{7}-\frac{4}{7}\right)+\left(-\frac{3}{8}+\frac{3}{8}\right)\)
\(=-1+1\)
\(=0\)