giúp mink bài câu 2 câu 3 câu 4 câu 6 câu 7
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Bài 4:
a: Ta có: \(-\left|x+1.1\right|\le0\forall x\)
\(\Leftrightarrow-\left|x+1.1\right|+1.5\le1.5\forall x\)
Dấu '=' xảy ra khi x=-1,1
b: Ta có: \(-4\left|x-2\right|\le0\forall x\)
\(\Leftrightarrow-4\left|x-2\right|+10\le10\forall x\)
Dấu '=' xảy ra khi x=2
\(\frac{12}{1}:\frac{6}{5}+\frac{4}{7}=\frac{60}{6}+\frac{7}{4}=\frac{10}{1}+\frac{7}{4}=\frac{40}{4}+\frac{7}{4}=\frac{47}{4}\)
\(\left(\frac{5}{6}+\frac{3}{4}\right)\cdot\frac{8}{19}=\frac{38}{24}\cdot\frac{18}{9}=\frac{38}{24}\cdot2=\frac{76}{24}=\frac{19}{6}\)
\(\left(\frac{7}{4}-\frac{5}{3}\right)\cdot\frac{2}{3}=\frac{1}{12}\cdot\frac{2}{3}=\frac{1}{13}\)
6.Although he had a good salary, he was unhappy in his job
In spite of his good salary he was unhappy in his job
7.) In spite of the forecast it stayed fine.
-> Although rain was predicted, it stayed fine
8.Although the team played well, they lost.
In spite of/Despite the fact that the team played well, they lost
Câu 1)
1/5*x=4/6
x=4/6/1/5
x=10/3
Câu 3)x/6*5/8=5/12
x/6=5/12/5/8
x/6=2/3
x/6=4/6
Vây x=4
Câu 3)
5/9/3/x=5/27
3/x=5/9/5/27
3/x=3
Vây x=1
Câu 2.
\(R_{13}=\dfrac{R_1\cdot R_3}{R_1+R_3}=\dfrac{30\cdot60}{30+60}=20\Omega\)
\(R_{tđ}=R_2+R_{13}=45+20=65\Omega\)
\(I_m=\dfrac{U}{R}=\dfrac{130}{65}=2A\)
\(I_{13}=I_m=2A\)
\(U_{13}=U-U_2=U-I_2\cdot R_2=130-2\cdot45=40V\)
\(R_1//R_3\Rightarrow U_1=U_3=U_{13}=40V\)
\(I_3=\dfrac{U_3}{R_3}=\dfrac{40}{60}=\dfrac{2}{3}A\)
Câu 3.
\(R_1//R_2\)
\(\Rightarrow R_{tđ}=\dfrac{R_1\cdot R_2}{R_1+R_2}=\dfrac{10\cdot30}{10+30}=7,5\Omega\)
\(U_1=U_2=U_m=15V\)
\(I_1=\dfrac{U_1}{R_1}=\dfrac{15}{10}=1,5A\)
\(I_2=\dfrac{U_2}{R_2}=\dfrac{15}{30}=0,5A\)
\(I_m=I_1+I_2=1,5+0,5=2A\)
3:
a: =>4,5(x+3)=18
=>x+3=4
=>x=1
b: =>x+1=5
=>x=4