B=11-(x-1)(x-3)
giúp mk câu này với. mk cần gấp
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Rồi sao? đề bài?
\(4(x+1)^2-(2x-1)^2-8(x-1)(x+1)=11\)
\(\Leftrightarrow4\left(x^2+2x+1\right)-\left(4x^2-4x+1\right)-8\left(x^2-1\right)=11\)
\(\Leftrightarrow4x^2+8x+4-4x^2+4x-1-8x^2+8=11\)
\(\Leftrightarrow-8x^2+12x+11=11\)
\(\Leftrightarrow-4x\left(2x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{3}{2}\end{matrix}\right.\)
Ta có:
\(4\left(x+1\right)^2-\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\\ \Leftrightarrow4x^2+8x+4-4x^2+4x-1-8x^2+8=11\\ \Leftrightarrow-8x^2+12x=0\\ \Leftrightarrow-4x\left(2x-3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{3}{2}\end{matrix}\right.\)
a)\(\left(x+8\right)-11=20-15\)
\(\left(x+8\right)-11=5\)
\( x+8=5+11\)
\(x+8=16\)
\(x=8\)
b) \(2x-\left(3+x\right)=5-7\)
\(2x-\left(3+x\right)=-2\)
\(2x-3-x=-2\)
\(x=1\)
c) \( \left(3x-2^4\right)\times7^5=2\times7^6\)
\(3x-2^4=2\times\left(7^6:7^5\right) \)
\(\left(3x-2^4\right)=2\times7^2\)
\(3x-2^4=2\times49\)
\(3x-16=98\)
\(3x=114\)
\(x=38\)
\(\frac{11}{12}-\frac{2}{3}|x|=\frac{3}{8}\)
\(\Rightarrow\frac{-2}{3}|x|=\frac{3}{8}-\frac{11}{12}\)
\(-\frac{2}{3}|x|=-\frac{13}{24}\)
\(|x|=\frac{13}{16}\)
\(\Rightarrow x=\hept{\begin{cases}\frac{13}{16}\\-\frac{13}{16}\end{cases}}\)
=.= hok tốt!!
\(\frac{1}{3}\left(x-1\right)+\frac{2}{5}\left(x+1\right)=0\)
\(\frac{1}{3}x-\frac{1}{3}+\frac{2}{5}x+\frac{2}{5}=0\)
\(\frac{11}{15}x+\left(\frac{2}{5}-\frac{1}{3}\right)=0\)
\(\frac{11}{15}x+\frac{1}{15}=0\)
\(\frac{1}{15}\left(11x+1\right)=0\)
\(11x+1=0\)
\(\Rightarrow x=-\frac{1}{11}\)