123 x (42 - 40) = 123 x 2 = 246

(100 + 11) x 9 = 111 x 9 = 999

a, 7875 : x = 45

x = 7875 : 45

x = 175

b, 25800:100 + 32 x 11 = 258 + 352 = 610

11 x 8 – 60 = 88 - 60 = 28

12 + 7 x 9 = 12 + 63 = 75

11 x 8 – 60 = 88 - 60 = 28

12 + 7 x 9 = 12 + 63 = 75

11 x 8 – 60 = 88 - 60

= 28

12 + 7 x 9 = 12 + 63

= 75

a: \(M=\dfrac{18+5x+15+3x-9}{\left(x+3\right)\left(x-3\right)}=\dfrac{8x+24}{\left(x+3\right)\left(x-3\right)}=\dfrac{8}{x-3}\)

b: Thay x=11 vào M, ta được:

\(M=\dfrac{8}{11-3}=1\)

a) \(M=\dfrac{18}{x^2-9}+\dfrac{5}{x-3}+\dfrac{3}{x+3}.\left(x\ne\pm3\right).\)

\(M=\dfrac{18}{\left(x-3\right)\left(x+3\right)}+\dfrac{5}{x-3}+\dfrac{3}{x+3}=\dfrac{18+5\left(x+3\right)+3\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)

\(=\dfrac{18+5x+15+3x-9}{\left(x-3\right)\left(x+3\right)}=\dfrac{24+8x}{\left(x-3\right)\left(x+3\right)}\)

\(=\dfrac{8\left(3+x\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{8}{x-3}.\)

b) Thay \(x=11\left(TM\right)\) vào biểu thức M: 

\(\dfrac{8}{11-3}=\dfrac{8}{8}=1.\)

\(=25\%+25\%\times38+25\%\times50+25\%\times11\)

\(=25\%\times\left(1+38+50+11\right)=25\%\times100=25\)

\(\dfrac{25}{100}+\dfrac{1}{4}\times38+25\%\times50+0,25\times11\)

\(0,25+0,25\times38+0,25\times50+0,25\times11+1\)

\(0,25\times\left(38+50+11+1\right)\)

\(0,25\times100\)

\(25\)

\(A=\left|x-101\right|-101\)

\(\left|x-101\right|\ge0\)

\(\Rightarrow\left|x-101\right|-101\ge-101\)

\(\Rightarrow A\ge101\)

\(\Rightarrow MIN_A=101\Leftrightarrow\left|x-101\right|=0\)

\(\Rightarrow x=101\)

vay_