Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a)\(\left(\frac{1}{5}\right)^{10}.5^{20}=\left(\frac{1}{5}\right)^{10}.5^{10.2}=\left(\frac{1}{5}\right)^{10}.25^{10}=\left(\frac{1}{5}.5\right)^{10}=1^{10}=1\)
b)\(5^2.3^5.\left(\frac{3}{5}\right)^2=\left(\frac{3}{5}.5\right)^2.3^5=3^2.3^5=3^7\)
c)\(\left(\frac{1}{16}\right)^3:\left(\frac{1}{8}\right)^2=\left(\frac{1}{8}\right)^{2.3}:\left(\frac{1}{8}\right)^2=\left(\frac{1}{8}\right)^{6+2}=\left(\frac{1}{8}\right)^8\)
\(a.\left(\frac{1}{5}\right)^{10}.5^{20}=\left(\frac{1}{5}\right)^{10}.5^{10.2}=\left(\frac{1}{5}\right)^{10}.\left(5^2\right)^{10}=\left(\frac{1}{5}\right)^{10}.25^{10}=\left(\frac{1}{5}.25\right)^{10}=5^{10}.\)
\(b.5^2.3^5.\left(\frac{3}{5}\right)^2=\left[5^2.\left(\frac{3}{5}\right)^2\right].3^5=\left(5.\frac{3}{5}\right)^2.3^5=3^2.3^5=3^7\)\(c.\left(\frac{1}{16}\right)^3:\left(\frac{1}{8}\right)^2=\left[\left(\frac{1}{4}\right)^2\right]^3:\left[\left(\frac{1}{2}\right)^3\right]^2=\left(\frac{1}{4}\right)^6:\left(\frac{1}{2}\right)^6=\left(\frac{1}{4}:\frac{1}{2}\right)^6=\left(\frac{1}{2}\right)^6\)
\(xy=\frac{1}{t}.txy\le\frac{t^2x^2+y^2}{2t}=\frac{\left(3+\sqrt{5}\right)x^2+y^2}{1+\sqrt{5}}\)\(t^2=\frac{3+\sqrt{5}}{2}\)
\(\frac{2\left(1+\sqrt{5}\right)\left(x^2+y^2+z^2+1\right)}{\left(3+\sqrt{5}\right)\left(2x^2+y^2+z^2+1\right)}\)
\(K=\frac{x^2+y^2+z^2+1}{xy+yz+z}=\frac{\left(1+\sqrt{5}\right)\left(x^2+y^2+z^2+1\right)}{2.\frac{1+\sqrt{5}}{2}x.y+\left(1+\sqrt{5}\right)yz+2.\frac{1+\sqrt{5}}{2}.z}\)
\(\ge\frac{\left(1+\sqrt{5}\right)\left(x^2+y^2+z^2+1\right)}{\frac{3+\sqrt{5}}{2}x^2+y^2+\frac{1+\sqrt{5}}{2}\left(y^2+z^2\right)+z^2+\frac{3+\sqrt{5}}{2}}=\frac{1+\sqrt{5}}{\frac{3+\sqrt{5}}{2}}=\sqrt{5}-1=k\)
Dấu "=" xảy ra khi \(\hept{\begin{cases}x=1\\y=\frac{1+\sqrt{5}}{2}\\z=\frac{1+\sqrt{5}}{2}\end{cases}}\)
\(M=\frac{x^2+y^2+z^2+1}{xy+y+z}=\frac{\left(\sqrt{5}-1\right)\left(x^2+y^2+z^2+1\right)}{2.x.\frac{\sqrt{5}-1}{2}y+\left(\sqrt{5}-1\right)y+2.\frac{\sqrt{5}-1}{2}.z}\)
\(\ge\frac{\left(\sqrt{5}-1\right)\left(x^2+y^2+z^2+1\right)}{x^2+\frac{3-\sqrt{5}}{2}y^2+\frac{\sqrt{5}-1}{2}\left(y^2+1\right)+\frac{3-\sqrt{5}}{2}+z^2}=\sqrt{5}-1=m\)
Dấu "=" xảy ra khi \(\hept{\begin{cases}x=\frac{-1+\sqrt{5}}{2}\\y=1\\z=\frac{-1+\sqrt{5}}{2}\end{cases}}\)
\(km+k+m=4\)
\(\frac{x-3}{5}=\frac{x+4}{-2}\)
=> (x - 3). (-2) = 5(x + 4)
=> -2x + 6 = 5x + 20
=> -2x - 5x = 20 - 6
=> -7x = 14
=> x = 14 : (-7)
=> x = -2
x-3/5=x+4/-2
=> ﴾x ‐ 3﴿. ﴾‐2﴿ = 5﴾x + 4﴿
=> ‐2x + 6 = 5x + 20
=> ‐2x ‐ 5x = 20 ‐ 6 => ‐7x = 14 => x = 14 : ﴾‐7﴿
=> x = ‐2
> =<
thay x=-1 ta có : \(\left(-x^2\right)+\left(-x^4\right)+\left(-x^6\right)+\left(-x^8\right)+....+\left(-x^{100}\right)\) =\(\left(-1^2\right)+\left(-1^4\right)+\left(-1^6\right)+\left(-1^8\right)+...+\left(-1^{100}\right)\) =1+1+1+1+...+1 = 50