Question

\(\dfrac{x+1}{9}=\dfrac{4}{x+1}\)

\(19.5^{2x+7}=475\)

\(33^x:11^x=243\)

\(\dfrac{2x}{5}=\dfrac{10}{x}\)

Answer 1

\(19.5^{2x+7}=475\\ \Rightarrow5^{2x+7}=25\\ \Rightarrow5^{2x+7}=5^2\\ \Rightarrow2x+7=2\\ \Rightarrow2x=-5\\ \Rightarrow x=-\dfrac{5}{2}\)

Answer 2

\(\dfrac{x+1}{9}=\dfrac{4}{x+1}\\ \Rightarrow\left(x+1\right)^2=9.4\\ \left(x+1\right)^2=36\\ \Rightarrow x+1=6\)

hoặc \(x+1=-6\)

TH1:

x+1=6

x=5

TH2:

x+1=-6

x=-5

Vậy...

Answer 3

\(\dfrac{x+1}{4}=\dfrac{9}{x+1}\)⇔(x+1)²=36(4*9)⇔x²+2x+1=36⇔x(x+2)=37

Answer 4

\(33^x:11^x=243\\ \Rightarrow\left(33:11\right)^x=243\\ \Leftarrow3^x=3^5\Rightarrow x=5\)

Answer 5

\(\dfrac{2x}{5}=\dfrac{10}{x}\\ \Rightarrow2x^2=50\\\Rightarrow x^2=25\\ \Rightarrow x=5\)

hoặc x=-5