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\(\dfrac{9^{15}\cdot8^{11}}{3^{29}\cdot16^8}=\dfrac{3^{2^{15}}\cdot2^{3^{11}}}{3^{29}\cdot2^{4^8}}=\dfrac{3^{30}\cdot2^{33}}{3^{29}\cdot2^{32}}\)
\(\Rightarrow\dfrac{3^{30}\cdot2^{33}}{3^{29}\cdot2^{32}}=\dfrac{3^{29}\cdot2^{32}\cdot3\cdot2}{3^{29}\cdot2^{32}}=3\cdot2=6\)
\(\dfrac{x+1}{199}+\dfrac{x+2}{198}+\dfrac{x+3}{197}+\dfrac{x+4}{196}+\dfrac{x+220}{5}=0\)
\(\Leftrightarrow\left(\dfrac{x+1}{199}+1\right)+\left(\dfrac{x+2}{198}+1\right)+\left(\dfrac{x+3}{197}+1\right)+\left(\dfrac{x+4}{196}+1\right)+\dfrac{x+200}{5}+\dfrac{20}{5}-4=0\)
\(\Leftrightarrow\dfrac{x+200}{199}+\dfrac{x+200}{198}+\dfrac{x+200}{197}+\dfrac{x+200}{196}+\dfrac{x+200}{5}=0\)
\(\Leftrightarrow\left(x+200\right)\left(\dfrac{1}{199}+\dfrac{1}{198}+\dfrac{1}{197}+\dfrac{1}{196}+\dfrac{1}{5}\right)=0\)
\(\Leftrightarrow x=-200\)( do \(\dfrac{1}{199}+\dfrac{1}{198}+\dfrac{1}{197}+\dfrac{1}{196}+\dfrac{1}{5}>0\))
\(\dfrac{x+1}{199}+\dfrac{x+2}{198}+\dfrac{x+3}{197}+\dfrac{x+4}{196}+\dfrac{x+220}{5}=0\\ \Leftrightarrow\left(\dfrac{x+1}{199}+1\right)+\left(\dfrac{x+2}{198}+1\right)+\left(\dfrac{x+3}{197}+1\right)+\left(\dfrac{x+4}{196}+1\right)+\left(\dfrac{x+220}{5}-4\right)=0\\ \Leftrightarrow\dfrac{x+200}{199}+\dfrac{x+200}{198}+\dfrac{x+200}{197}+\dfrac{x+200}{196}+\dfrac{x+200}{5}=0\\ \Leftrightarrow\left(x+200\right)\left(\dfrac{1}{199}+\dfrac{1}{198}+\dfrac{1}{197}+\dfrac{1}{196}+\dfrac{1}{5}\right)=0\\ \Leftrightarrow x=-200\)
Mình xin phép sửa đề: `x/5=y/3` và `x^3-y^3=98`
Đặt `x/5=y/3=K`
`-> x=5K, y=3K`
`x^3-y^3=98 -> (5K)^3-(3K)^3=98`
`-> 98K^6=98`
`-> K^6=98 \div 98`
`-> K^6=(+-1)^6`
`-> K=1 ; -1`
Với `K=1 -> x=5*1=5 ; y=3*1=3`
Với `K=-1 -> x=5*(-1)=-5 l y=3*(-1)=-3`
mình có đáp án rồi, mik cần bài này dười dạng tự luận cơ