giúp mình với : a/4 - 2/b = 5/4
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\(1,\sqrt{4\left(a-4\right)^2}\left(dkxd:a\ge4\right)\)
\(=\sqrt{4}.\sqrt{\left(a-4\right)^2}\)
\(=\sqrt{2^2}.\left|a-4\right|\)
\(=2\left(a-4\right)\)
\(=2a-8\)
\(2,\sqrt{9\left(b-5\right)^2}\left(dkxd:b< 5\right)\)
\(=\sqrt{9}.\sqrt{\left(b-5\right)^2}\)
\(=\sqrt{3^2}.\left|b-5\right|\)
\(=3\left(-b+5\right)\)
\(=-3b+15\)
TL
x - \(\frac{4}{5}\)=\(\frac{2}{3}\)
x =\(\frac{2}{3}+\frac{4}{5}\)
x =\(\frac{22}{15}\)
3x-\(\frac{1}{2}=\frac{4}{3}\)
3x \(=\frac{4}{3}+\frac{1}{2}\)
3x \(=\frac{11}{6}\)
x = \(\frac{11}{6}:3\)
x =\(\frac{11}{18}\)
nha bn
HT
a. ĐKXĐ: \(x\ne1\)
\(\dfrac{11x-4}{x-1}+\dfrac{10x+4}{2-2x}=\dfrac{2\cdot\left(11x-4\right)}{2\cdot\left(x-1\right)}-\dfrac{10x+4}{2x-2}\)
\(=\dfrac{22x-8}{2\left(x-1\right)}-\dfrac{10x+4}{2\left(x-1\right)}\)\(=\dfrac{22x-8-10x-4}{2\left(x-1\right)}\)
\(=\dfrac{12x-12}{2\left(x-1\right)}\)\(=\dfrac{12\left(x-1\right)}{2\left(x-1\right)}=6\)
b. ĐKXĐ: \(x\ne-2;x\ne\dfrac{1}{2}\)
\(\dfrac{1}{x+2}+\dfrac{5}{2x^2+3x-2}=\dfrac{2x-1}{\left(2x-1\right)\left(x+2\right)}+\dfrac{5}{\left(2x-1\right)\left(x+2\right)}\)
\(=\dfrac{2x-1+5}{\left(2x-1\right)\left(x+2\right)}=\dfrac{2x+4}{\left(2x-1\right)\left(x+2\right)}\)
\(=\dfrac{2\left(x+2\right)}{\left(2x-1\right)\left(x+2\right)}=\dfrac{2}{2x-1}\)
\(\text{#}Toru\)
a) \(...=-\dfrac{1}{4}.\dfrac{4}{17}.\left(-\dfrac{63}{21}\right).\left(-\dfrac{7}{12}\right)\)
\(=-\dfrac{1}{17}.\dfrac{63}{21}.\dfrac{7}{12}\)
\(=-\dfrac{7}{68}\)
b) \(...=-\dfrac{2}{5}.\dfrac{4}{15}-\dfrac{3}{10}.\dfrac{4}{15}\)
\(=\dfrac{4}{15}\left(-\dfrac{2}{5}-\dfrac{3}{10}\right)\)
\(=\dfrac{4}{15}\left(-\dfrac{4}{10}-\dfrac{3}{10}\right)\)
\(=\dfrac{4}{15}.\left(-\dfrac{7}{10}\right)=-\dfrac{14}{75}\)
c) \(...=21-\dfrac{15}{4}:\left(\dfrac{9}{24}-\dfrac{4}{24}\right)\)
\(=21-\dfrac{15}{4}:\dfrac{5}{24}\)
\(=21-\dfrac{15}{4}.\dfrac{24}{5}\)
\(=21-3.6=3\)
d) \(...=\left(-\dfrac{3}{4}+\dfrac{2}{5}\right).\dfrac{7}{3}+\left(\dfrac{3}{5}-\dfrac{1}{4}\right).\dfrac{7}{3}\)
\(=\dfrac{7}{3}\left(-\dfrac{3}{4}+\dfrac{2}{5}+\dfrac{3}{5}-\dfrac{1}{4}\right)\)
\(=\dfrac{7}{3}\left(-\dfrac{3}{4}-\dfrac{1}{4}+\dfrac{2}{5}+\dfrac{3}{5}\right)\)
\(=\dfrac{7}{3}\left(-1+1\right)=0\)
a. =[(-4)(-25)].3=100.3=300
b. =[(-8).125][5.2]=-1000.10=-10000
c. =[25.(-4)][(-5).20]=-100(-100)=10000
bủh
$a,b$ có điều kiện gì không bạn?