rút gọn.
\(\frac{x\sqrt{x}-2x+28}{x-3\sqrt{x}}-\frac{\sqrt{x}-4}{\sqrt{x}+1}+\frac{\sqrt{x}+8}{4-\sqrt{x}}\)
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=\(\frac{x\sqrt{x}-2x+28}{x-3\sqrt{x}-4}\)- \(\frac{\sqrt{x}-4}{\sqrt{x}+1}\)- \(\frac{\sqrt{x}+8}{\sqrt{x}-4}\)
= \(\frac{x\sqrt{x}-2x+28-\left(x-16\right)-\left(\sqrt{x}+1\right)\left(\sqrt{x}+8\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)
=\(\frac{x\sqrt{x}-2x+28-x+16-\left(x+9\sqrt{x}+8\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)
=\(\frac{x\sqrt{x}-3x+44-x-9\sqrt{x}-8}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)
=\(\frac{x\sqrt{x}-9\sqrt{x}-4x+36}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)
=\(\frac{\sqrt{x}\left(x-9\right)-4\left(x-9\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)= \(\frac{\left(\sqrt{x}-4\right)\left(x-9\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}\)
=\(\frac{x-9}{\sqrt{x}+1}\)
ĐK:x\(\ge0,x\ne16\)
\(\frac{x\sqrt{x}-2x+28}{x-3\sqrt{x}-4}-\frac{\sqrt{x}-4}{\sqrt{x}+1}-\frac{\sqrt{x}+8}{\sqrt{x}-4}=\frac{x\sqrt{x}-2x+28}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}-\frac{\left(\sqrt{x}-4\right)^2}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}-\frac{\left(\sqrt{x}+8\right)\left(\sqrt{x}+1\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{x\sqrt{x}-2x+28}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}-\frac{x-8\sqrt{x}+16}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}-\frac{x+9\sqrt{x}+8}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{x\sqrt{x}-2x+28-x+8\sqrt{x}-16-x-9\sqrt{x}-8}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{x\sqrt{x}-4x-\sqrt{x}+4}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{x\left(\sqrt{x}-4\right)-\left(\sqrt{x}-4\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{\left(\sqrt{x}-4\right)\left(x-1\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\frac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)\left(\sqrt{x}-1\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-4\right)}=\sqrt{x}-1\)
sai đề. Mẫu phân thức thứ 1 là \(x-3\sqrt{x}-4\)
Đây là đề lớp 10 nh 11-12 của TPHCM