\(A=-1,6:\left(1+\frac{2}{3}\right)\)

\(A=\frac{-8}{5}:\frac{5}{3}=-\frac{8}{5}.\frac{3}{5}=\frac{-24}{25}\)

\(B=\frac{7}{5}.\frac{15}{29}-\left(\frac{4}{5}+\frac{2}{3}\right):\frac{11}{5}\)

\(B=\frac{21}{29}-\left(\frac{12}{15}+\frac{10}{15}\right).\frac{5}{11}=\frac{21}{29}-\frac{22}{15}.\frac{5}{11}=\frac{21}{29}-\frac{2}{3}\)

\(B=\frac{63}{87}-\frac{58}{87}=\frac{5}{87}\)

A= -8/5: (1+2/3)

 = -8/5:5/3

 = -8/5.3/5

 = -24/25

B= 7/5.15/49-22/15: 11/5

 = 3/7-2/5

 = 1/35

\(A=-1,6:\left(1+\frac{2}{3}\right)\)

\(A=-1,6:\frac{5}{3}\)

\(A=-\frac{24}{25}\)

\(B=1,4.\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)

\(B=\frac{135}{98}-\frac{2}{3}\)

\(B=\frac{209}{294}\)

\(1)A=a\frac{1}{3}+a\frac{1}{4}-a\frac{1}{6}=a\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{6}\right)=a\frac{5}{12}\)

Thay \(a=-\frac{3}{5}\) vào A,ta đc:

\(A=-\frac{3}{5}.\frac{5}{12}=-\frac{1}{4}\)

\(2)B=b\frac{5}{6}+b\frac{3}{4}-b\frac{1}{2}=b\left(\frac{5}{6}+\frac{3}{4}-\frac{1}{2}\right)=b\frac{13}{12}\)

Thay \(b=\frac{12}{13}\) vào B, ta đc: \(B=b\frac{13}{12}=\frac{12}{13}.\frac{13}{12}=1\)

a ,A = \(a.\frac{1}{3}+a.\frac{1}{4}-a.\frac{1}{6}\)

      \(=a.\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{6}\right)\)

       \(=\frac{-3}{5}.\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{6}\right)\\ =\frac{-3}{5}.\frac{5}{12}\)

          \(=\frac{-1}{4}\)    

b,  B = \(b.\frac{5}{6}+b.\frac{3}{4}-b.\frac{1}{2}\)

        \(=b.\left(\frac{5}{6}+\frac{1}{4}-\frac{1}{2}\right)\)

         \(=\frac{12}{13}.\left(\frac{5}{6}+\frac{1}{4}-\frac{1}{2}\right)\)

          \(=\frac{12}{13}.\frac{7}{12}\)

           \(=\frac{7}{13}\)

a) Thay \(a=\frac{-3}{5}\)vào biểu thức A ta có :

\(A=\frac{-3}{5}.\frac{1}{3}+\frac{-3}{5}.\frac{1}{4}-\frac{-3}{5}.\frac{1}{6}\)

\(A=\frac{-3}{5}.\left(\frac{1}{3}+\frac{1}{4}-\frac{1}{6}\right)\)

\(A=\frac{-3}{5}.\frac{5}{12}\)

\(A=\frac{-1}{4}\)

Vậy giá trị của biểu thức A tại \(a=\frac{-3}{5}\)là \(\frac{-1}{4}\)

b) Thay \(b=\frac{12}{13}\)vào biểu thức B ta có :

\(B=\frac{12}{13}.\frac{5}{6}+\frac{12}{13}.\frac{3}{4}-\frac{12}{13}.\frac{1}{2}\)

\(B=\frac{12}{13}.\left(\frac{5}{6}+\frac{3}{4}-\frac{1}{2}\right)\)

\(B=\frac{12}{13}.\frac{13}{12}\)

\(B=1\)

Vậy giá trị của biểu thức B tại \(b=\frac{12}{13}\)là 1

_Chúc bạn học tốt_

mik ko hieu lam

.

Áp dụng tính chất phân phối, rồi tính giá trị biểu thức.

Chẳng hạn,

Với , thì

ĐS. ; C = 0.

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\(A=\frac{2^{12}x3^4x3^{10}}{2^{12}x3^{12}}=3^2=9\)

\(A=\frac{4^6.3^4.9^5}{6^{12}}\)

\(A=\frac{\left(2^2\right)^6.3^4.\left(3^2\right)^5}{\left(2.3\right)^{12}}\)

\(A=\frac{2^{12}.3^4.3^{10}}{2^{12}.3^{12}}\)

\(A=\frac{2^{12}.3^{14}}{2^{12}.3^{12}}\)

\(A=3^2\left(2^{12}.3^{12}\ne0\right)\)

\(A=9\)

Vậy \(A=9\)

A=\(\frac{72^3.54^2}{108^4}=\frac{\left(2^3.3^2\right)^3.\left(2.3^3\right)^2}{\left(2^2.3^3\right)^4}=\frac{2^9.3^6.2^2.3^6}{2^8.3^{12}}=\frac{2^{11}.3^{12}}{2^8.3^{12}}=2^3=8\)

B= \(\frac{4^6.3^4.9^5}{6^{12}}=\frac{2^{12}.3^4.3^{10}}{2^{12}.3^{12}}=\frac{2^{12}.3^{14}}{2^{12}.3^{12}}=3^2=9\)

c) \(\frac{2^{13}+2^5}{2^{10}+2^2}=\frac{2^5\left(2^8+1\right)}{2^2\left(2^8+1\right)}=2^3=8\)

1.

\(\frac{72^3\times54^2}{108^4}=\frac{\left(8\times9\right)^3\times\left(27\times2\right)^2}{\left(27\times4\right)^4}=\frac{\left(2^3\times3^2\right)^3\times\left(3^3\times2\right)^2}{\left(3^3\times2^2\right)^4}=\frac{\left(2^3\right)^3\times\left(3^2\right)^3\times\left(3^3\right)^2\times2^2}{\left(3^3\right)^4\times\left(2^2\right)^4}=\frac{2^9\times3^6\times3^6\times2^2}{3^{12}\times2^8}=2^3=8\)

2.

\(\frac{4^6\times3^4\times9^5}{6^{12}}=\frac{\left(2^2\right)^6\times3^4\times\left(3^2\right)^5}{\left(2\times3\right)^{12}}=\frac{2^{12}\times3^4\times3^{10}}{2^{12}\times3^{12}}=3^2=9\)

3.

\(\frac{2^{13}+2^5}{2^{10}+2^2}=\frac{2^5\times\left(2^8+1\right)}{2^2\times\left(2^8+1\right)}=2^3=8\)