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Ta có:\(\left(\frac{6}{x^2-6x}+\frac{1}{x+6}\right):\frac{x^2+36}{x^2-36}\)
\(=\left(\frac{6\left(x+6\right)}{x\left(x-6\right)\left(x+6\right)}+\frac{x\left(x-6\right)}{x\left(x-6\right)\left(x+6\right)}\right).\frac{x^2-6^2}{x^2+36}\)
\(=\left(\frac{6x+36+x^2-6x}{x\left(x-6\right)\left(x+6\right)}\right).\frac{\left(x-6\right)\left(x+6\right)}{x^2+36}\)
\(=\frac{x^2+36}{x\left(x-6\right)\left(x+6\right)}.\frac{\left(x-6\right)\left(x+6\right)}{x^2+36}\)
\(=\frac{1}{x}\)
Kiểm tra đi bạn phải là \(\frac{1}{x}\)
\(\left(\frac{x}{x^2-36}+\frac{6-x}{x^2+6x}\right):\frac{2x-6}{x^2+6x}+\frac{x}{6-x}\)
đkxđ: \(x\ne0;x\ne\pm6\)
MTC=x(x+6)(x-6)
\(=\left[\frac{x}{\left(x+6\right)\left(x-6\right)}+\frac{6-x}{x\left(x+6\right)}\right]\cdot\frac{x\left(x+6\right)}{x\left(x-3\right)}-\frac{x}{x-6}\)
\(=\left[\frac{x^2}{x\left(x^2-36\right)}-\frac{\left(x-6\right)^2}{x\left(x^2-36\right)}\right]\cdot\frac{x\left(x+6\right)}{x\left(x-3\right)}-\frac{x}{x-6}\)
\(=\frac{12\left(x-3\right)}{x\left(x+6\right)\left(x-6\right)}\cdot\frac{x\left(x+6\right)}{x\left(x-3\right)}-\frac{x}{x-6}\)
\(=\frac{12}{x\left(x-6\right)}-\frac{x^2}{x\left(x-6\right)}\)
\(=\frac{12-x^2}{x\left(x-6\right)}\)
.....................
A = \(\left(\frac{x}{x^2-36}-\frac{x-6}{x^2+6x}\right):\frac{2x-6}{x^2+6x}+\frac{x}{6-x}\)
= \(\left[\frac{x}{\left(x-6\right)\left(x+6\right)}-\frac{x-6}{x\left(x+6\right)}\right]:\frac{2\left(x-3\right)}{x\left(x+6\right)}-\frac{x}{x-6}\)
= \(\left[\frac{x^2}{x\left(x-6\right)\left(x+6\right)}-\frac{\left(x-6\right)^2}{x\left(x-6\right)\left(x+6\right)}\right]:\frac{2\left(x-3\right)}{x\left(x+6\right)}-\frac{x}{x-6}\)
= \(\frac{x^2-\left(x-6\right)^2}{x\left(x-6\right)\left(x+6\right)}:\frac{2\left(x-3\right)}{x\left(x+6\right)}-\frac{x}{x-6}\)
= \(\frac{\left(x-x+6\right)\left(x+x-6\right)}{x\left(x-6\right)\left(x+6\right)}:\frac{2\left(x-3\right)}{x\left(x+6\right)}-\frac{x}{x-6}\)
=
= \(\frac{x\left(2x-6\right)}{x\left(x-6\right)\left(x+6\right)}:\frac{2x-6}{x\left(x+6\right)}-\frac{x}{x-6}\)
= \(\frac{2x-6}{\left(x-6\right)\left(x+6\right)}.\frac{x\left(x+6\right)}{2x-6}\) \(-\frac{x}{x-6}\)
= \(\frac{x}{x-6}-\frac{x}{x-6}\)
= 0
Xem lại đề gõ thiếu không? Ở \(\frac{2x-6}{x^2+6}\) phải là \(\frac{2x-6}{x^2+6x}\) chứ nhỉ
Sửa lại đề của bạn nhé
\(\left(\frac{x}{x^2-36}-\frac{x-6}{x^2+6x}\right):\frac{2x-6}{x^2+6x}+\frac{x}{6-x}\\ =\left(\frac{x}{\left(x-6\right)\left(x+6\right)}-\frac{x-6}{x\left(x+6\right)}\right).\frac{x\left(x+6\right)}{2x-6}+\frac{-x}{x-6}\\ =\left(\frac{x^2}{x\left(x-6\right)\left(x+6\right)}-\frac{\left(x-6\right)^2}{x\left(x-6\right)\left(x+6\right)}\right).\frac{x\left(x+6\right)}{2x-6}+\frac{-x}{x-6}\\ =\frac{\left(x-x+6\right)\left(x+x-6\right)}{x\left(x-6\right)\left(x+6\right)}.\frac{x\left(x+6\right)}{2x-6}+\frac{-x}{x-6}\\ =\frac{6\left(2x-6\right)}{x\left(x-6\right)\left(x+6\right)}.\frac{x\left(x+6\right)}{2x-6}+\frac{-x}{x-6}\\ =\frac{6x\left(2x-6\right)\left(x+6\right)}{x\left(x-6\right)\left(x+6\right)\left(2x-6\right)}+\frac{-x}{x-6}\\ =\frac{6}{x-6}+\frac{-x}{x-6}\\ =\frac{6-x}{x-6}\\ =-1\left(đpcm\right)\)
\(\left(\frac{x+1}{39}+1\right)+\left(\frac{x+2}{38}+1\right)=\left(\frac{x+3}{37}+1\right)+\left(\frac{x+4}{36}+1\right)\)
\(\Leftrightarrow\frac{x+40}{39}+\frac{x+40}{38}-\frac{x+40}{37}-\frac{x+40}{36}=0\)
\(\Leftrightarrow\left(x+40\right)\left(\frac{1}{39}+\frac{1}{38}-\frac{1}{37}-\frac{1}{36}\right)=0\)
<=> x+40=0 (vì \(\frac{1}{39}+\frac{1}{38}-\frac{1}{37}-\frac{1}{36}\ne\)0)
<=> x=-40
Vậy x=-40
a) Ta có: 3x-6=0
⇔3(x-2)=0
mà 3≠0
nên x-2=0
hay x=2
Vậy: x=2
b) Ta có: (2x+6)(2x+12)=0
⇔\(2\left(x+3\right)\cdot2\cdot\left(x+6\right)=0\)
mà 2≠0
nên \(\left[{}\begin{matrix}x+3=0\\x+6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-6\end{matrix}\right.\)
Vậy: x∈{-3;-6}
c) Ta có: 2x-36=0
⇔2(x-18)=0
mà 2≠0
nên x-18=0
hay x=18
Vậy: x=18
d) ĐKXĐ: x∉{-1;2}
Ta có: \(\frac{1}{x+1}-\frac{5}{x-2}=\frac{-15}{\left(x+1\right)\left(x-2\right)}\)
\(\Leftrightarrow\frac{x-2}{\left(x+1\right)\left(x-2\right)}-\frac{5\left(x+1\right)}{\left(x-2\right)\left(x+1\right)}=\frac{-15}{\left(x+1\right)\left(x-2\right)}\)
\(\Leftrightarrow x-2-5\left(x+1\right)=-15\)
\(\Leftrightarrow x-2-5x-5+15=0\)
\(\Leftrightarrow-4x+8=0\)
\(\Leftrightarrow-4\left(x-2\right)=0\)
mà -4≠0
nên x-2=0
hay x=2(ktm)
Vậy: x∈∅
= ( x/(x-6)(x+6) - x-6/x(x+6) ) : 2x-6/x2 + 6x + 6/6-x
=( x2/x(x+6)(x-6) - (x -6 )(x-6)/x(x+6)(x-6) ) : .....
= (12x -36 / x(x+6)(x-6) : 2x-6/ x2 + 6x )+ 6/6-x
=6/x-6 + 6/6-x
= 6-6/ x-6
=0/x-6
câu trước mình thiếu 6/6-x
\(72\left(x-6\right)+72\left(x+6\right)=9\left(x^2-36\right)\)
\(144x=9x^2-324\)=0
\(9x^2-144x-324=0\)
\(9\left(x^2-16x-36\right)=0\)
\(9\left(x^2-18x+2x-36\right)=0\)
\(9\left(x-18\right)\left(x+2\right)=0\)
Đến đây bạn tự làm nhé