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dien h trong cay chiem
1-1|4-1/6=3/12[s]
\(\dfrac{4}{5}+\dfrac{19}{18}-\dfrac{1}{2}+\dfrac{1}{5}-\dfrac{10}{8}\)
\(=\left(\dfrac{4}{5}+\dfrac{1}{5}\right)-\left(\dfrac{4}{8}+\dfrac{10}{8}\right)+\dfrac{19}{18}\)
\(=\dfrac{5}{5}-\dfrac{14}{8}+\dfrac{19}{18}\)
\(=1-\dfrac{7}{4}+\dfrac{19}{18}\)
\(=-\dfrac{3}{4}+\dfrac{19}{18}=\dfrac{11}{36}\)
\(\dfrac{4}{5}+\dfrac{19}{18}-\dfrac{1}{2}+\dfrac{1}{5}-\dfrac{10}{8}=\dfrac{4}{5}+\dfrac{19}{18}-\dfrac{1}{2}+\dfrac{1}{5}-\dfrac{5}{4}=\left(\dfrac{4}{5}+\dfrac{1}{5}\right)+\left(\dfrac{19}{18}-\dfrac{1}{2}\right)-\dfrac{5}{4}=1+\dfrac{5}{9}-\dfrac{5}{4}=\dfrac{36}{36}+\dfrac{20}{36}-\dfrac{45}{36}=\dfrac{11}{36}\)
1) \(\left(2x+3\right)^2=4x^2+12x+9\)
\(\left(3x+2\right)^2=9x^2+12x+4\)
\(\left(2x+5\right)^2=4x^2+20x+25\)
\(\left(2x+\dfrac{1}{3}\right)^2=4x^2+\dfrac{4}{3}x+\dfrac{1}{9}\)
\(\left(3x+\dfrac{1}{3}\right)^2=9x^2+2x+\dfrac{1}{9}\)
2) \(\left(2x-3\right)^2=4x^2-12x+9\)
\(\left(3x-2\right)^2=9x^2-12x+4\)
\(\left(2x-5\right)^2=4x^2-20x+25\)
\(\left(2x-\dfrac{1}{3}\right)^2=4x^2-\dfrac{4}{3}x+\dfrac{1}{9}\)
\(\left(3x-\dfrac{1}{3}\right)^2=9x^2-2x+\dfrac{1}{9}\)
3) \(\left(2x-3\right)\left(2x+3\right)=4x^2-9\)
\(\left(3x-4\right)\left(3x+4\right)=9x^2-16\)
\(\left(2x-5\right)\left(2x+5\right)=4x^2-25\)
\(\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)=x^2-\dfrac{1}{4}\)
\(\left(2x-\dfrac{1}{3}\right)\left(2x+\dfrac{1}{3}\right)=4x^2-\dfrac{1}{9}\)
1: \(\left(2x+3\right)^2=4x^2+12x+9\)
\(\left(3x+2\right)^2=9x^2+12x+4\)
\(\left(2x+5\right)^2=4x^2+20x+25\)
\(\left(2x+\dfrac{1}{3}\right)^2=4x^2+\dfrac{4}{3}x+\dfrac{1}{9}\)
\(\left(3x+\dfrac{1}{3}\right)^2=9x^2+2x+\dfrac{1}{9}\)
Bài 3:
a. \(R=p\dfrac{l}{S}=1,1.10^{-6}\dfrac{30}{0,2.10^{-6}}=165\Omega\)
b. \(Q=UIt=220\left(\dfrac{220}{165}\right).15.60=254000\left(J\right)\)
Bài 2:
a. \(R=\dfrac{U^2}{P}=\dfrac{220^2}{1000}=48,4\Omega\)
b. \(Q=UIt=220\left(\dfrac{220}{48,4}\right).4.3600=14400000\left(J\right)\)
c. \(Q'=Q.40=14400000.40=576000000\left(J\right)=120000\)kWh
\(\Rightarrow T=Q'.2100=120000.2100=252000000\left(dong\right)\)
1 sai đề
2 B
3 C
4 A
5 A