25.(-1/5)^3+1/5-3.(-1/3)^2-1/9
giúp mik vs!
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\(\dfrac{-4}{x}=\dfrac{x}{-49}\\ \Rightarrow x^2=\left(-4\right)\left(-49\right)\\ \Rightarrow x^2=196\\ \Rightarrow x=\pm14\)
\(\dfrac{3.6}{x-3}=\dfrac{5}{3}\\ \Rightarrow5\left(x-3\right)=3.3.6\\ \Rightarrow5\left(x-3\right)=54\\ \Rightarrow x-3=\dfrac{54}{5}\\ \Rightarrow x=\dfrac{54}{5}+3\\ \Rightarrow x=\dfrac{69}{15}\)
\(\left(2x+1\right):2=12:3\\ \left(2x+1\right):2=4\\2x+1=2\\ 2x=1\\ x=\dfrac{1}{2} \)
\(\left(2x-14\right):3=12:9\\ \left(2x-14\right):3=\dfrac{4}{3}\\ 2x-14=4\\ 2x=16\\ x=8\)
\(P=4^{25}\cdot\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\cdot\left(\dfrac{1}{2}-\dfrac{1}{5}\right)\cdot\left(\dfrac{1}{2}-\dfrac{1}{7}\right)\cdot...\cdot\left(\dfrac{1}{2}-\dfrac{1}{101}\right)\)
\(P=4^{25}\cdot\left(\dfrac{1}{2}\cdot\left(\dfrac{1}{3}+\dfrac{1}{5}+\dfrac{1}{7}-...+\dfrac{1}{101}\right)\right)\)
\(P=4^{25}\cdot\left(\dfrac{1}{2}\cdot\left(\dfrac{1}{101}-\dfrac{1}{3}\right)\div2+1\right)\)
\(P=4^{25}\cdot\left(\dfrac{1}{2}\cdot\dfrac{1}{50}\right)\)
\(P=4^{25}\cdot\dfrac{1}{100}\)
Câu 1:72.(-2)2+(-2) 2 .28
= (-2)2 . ( 72 + 28 )
= 4 . 100
= 400
Câu 2: (-25).(75-45)-75.(45-25)
= (-25) . 75 + 25 . 45 - 75 . 45 + 75 . 25
= 25 . 45 - 75 . 45
= 45 . ( 25 - 75 )
= 45 . -50
= -2250
Câu 3:a+1 là ước của 5
\(\Rightarrow\)a + 1 \(\in\){ 1 ; -1 ; 5 ; -5 }
\(\Rightarrow\)a \(\in\){ 0 ; -2 ; 4 ; -6 }
Vậy a \(\in\){ 0 ; -2 ; 4 ; -6 }
~ HOK TỐT ~
a: \(=\left(1+\dfrac{\sqrt{5}\left(\sqrt{5}-1\right)}{-\left(\sqrt{5}-1\right)}\right)\left(\sqrt{5}+1\right)\)
=(1-căn 5)(1+căn 5)
=1-5=-4
b: \(=\sqrt{3}+\sqrt{2}+\sqrt{3}-\sqrt{2}=2\sqrt{3}\)
\(\frac{25.5^3.1}{625.5^2}=\frac{5^2.5^3}{5^4.5^2}=\frac{1}{5}\)
các câu sau mk k hiểu bn viết j