mong các bạn giúp đỡ mình đang cần gấp
\(\sqrt{\frac{2}{x^2}}\)
\(\frac{\sqrt{5}+2}{\sqrt{5}-2}\)
Mình cần gấp mong các bạn giúp đỡ
Bài làm:
\(\frac{\sqrt{5}+2}{\sqrt{5}-2}=\frac{\left(\sqrt{5}+2\right)^2}{\left(\sqrt{5}-2\right)\left(\sqrt{5}+2\right)}=\frac{5+2.2.\sqrt{5}+4}{5-4}\)
\(=9+4\sqrt{5}\)
Học tốt!!!!
\(\frac{\sqrt{5}+2}{\sqrt{5}-2}=\frac{5+2\sqrt{5}+4+2\sqrt{5}}{\sqrt{5}^2-2^2}\)
\(=\frac{9+4\sqrt{5}}{5-4}=9+4\sqrt{5}\)
@Học tốt@
Trả lời
\(\frac{\sqrt{5}+2}{\sqrt{5}-2}=\frac{\left(\sqrt{5}+2\right).\left(\sqrt{5}+2\right)}{\left(\sqrt{5}-2\right).\left(\sqrt{5}+2\right)}\)
\(=\frac{5+4\sqrt{5}+4}{5-4}\)
\(=\frac{9+4\sqrt{5}}{1}\)
\(=9+4\sqrt{5}\)
\(\frac{2}{\sqrt{5}+\sqrt{3}}-\sqrt{\frac{2}{4-\sqrt{15}}}+6\sqrt{\frac{1}{3}}\)
mình cần gấp mong các bạn giúp đỡ
Trả lời:
\(\frac{2}{\sqrt{5}+\sqrt{3}}-\sqrt{\frac{2}{4-\sqrt{15}}}+6\sqrt{\frac{1}{3}}\)
\(=\frac{2.\left(\sqrt{5}-\sqrt{3}\right)}{5-3}-\sqrt{\frac{2\times2}{2\times\left(4-\sqrt{15}\right)}}+6\times\frac{1}{\sqrt{3}}\)
\(=\frac{2.\left(\sqrt{5}-\sqrt{3}\right)}{2}-\sqrt{\frac{4}{8-2\sqrt{15}}}+6\times\frac{\sqrt{3}}{3}\)
\(=\sqrt{5}-\sqrt{3}-\sqrt{\frac{4}{5-2\sqrt{15}+3}}+2\sqrt{3}\)
\(=\sqrt{5}-\sqrt{3}-\sqrt{\frac{4}{\left(\sqrt{5}-\sqrt{3}\right)^2}}+2\sqrt{3}\)
\(=\sqrt{5}-\sqrt{3}-\frac{2}{\sqrt{5}-\sqrt{3}}+2\sqrt{3}\)
\(=\sqrt{5}+\sqrt{3}-\frac{2}{\sqrt{5}-\sqrt{3}}\)
\(=\frac{\left(\sqrt{5}-\sqrt{3}\right).\left(\sqrt{5}+3\right)-2}{\sqrt{5}-\sqrt{3}}\)
\(=\frac{5-3-2}{\sqrt{5}-\sqrt{3}}\)
\(=0\)
Học tốt
\(\frac{2}{\sqrt{5}+\sqrt{3}}-\sqrt{\frac{2}{4-\sqrt{15}}}+6\sqrt{\frac{1}{3}}\)
mình cần gấp mong các bạn giúp đỡ
\(\left(\frac{\sqrt{5}}{\sqrt{2}+1}+\frac{14}{2\sqrt{2}-1}-\frac{6}{2-\sqrt{2}}\right).\sqrt{17-12\sqrt{2}}\)
mình cần gấp mong các bạn giúp đỡ
\(\frac{2\sqrt{5}-5\sqrt{2}}{\sqrt{2}-\sqrt{5}}+\frac{6}{2-\sqrt{10}}+\sqrt{67+12\sqrt{7}}\)
mình cần gấp mong các bạn giúp đỡ
Trả lời:
\(\frac{2\sqrt{5}-5\sqrt{2}}{\sqrt{2}-\sqrt{5}}+\frac{6}{2-\sqrt{10}}+\sqrt{67+12\sqrt{7}}\)
\(=\frac{\sqrt{2}.\sqrt{5}.\left(\sqrt{2}-\sqrt{5}\right)}{\sqrt{2}-\sqrt{5}}-\frac{6}{\sqrt{10}-2}+\sqrt{63+12\sqrt{7}+4}\)
\(=\sqrt{2}.\sqrt{5}-\frac{6.\left(\sqrt{10}+2\right)}{10-4}+\sqrt{\left(3\sqrt{7}+2\right)^2}\)
\(=\sqrt{10}-\sqrt{10}-2+3\sqrt{7}+2\)
\(=3\sqrt{7}\)
\(\sqrt{4x-20}-3\sqrt{\frac{x-5}{9}}=\sqrt{1-x}\)
mình cần gấp mong các bạn giúp đỡ
\(\frac{\sqrt{7}-\sqrt{5}}{\sqrt{7+\sqrt{5}}}\)
Mình cần gấp mong các bạn giúp đỡ
Bài làm:
Ta có: \(\frac{\sqrt{7}-\sqrt{5}}{\sqrt{7}+\sqrt{5}}=\frac{\left(\sqrt{7}-\sqrt{5}\right)^2}{\left(\sqrt{7}+\sqrt{5}\right)\left(\sqrt{7}-\sqrt{5}\right)}=\frac{7-2.\sqrt{7}.\sqrt{5}-5}{7-5}\)
\(=\frac{2-2\sqrt{35}}{2}=1-\sqrt{35}\)
Học tốT!!!!
\(\frac{x+3}{x-3}-\frac{17}{x^2-9}=\frac{x-3}{x+3}\)
mình cần gấp mong các bạn giúp đỡ
\(ĐKXĐ:x\ne\pm3\)
\(pt\Leftrightarrow\frac{\left(x+3\right)^2-\left(x-3\right)^2}{x^2-9}=\frac{17}{x^2-9}\)
\(\Leftrightarrow\left(x+3\right)^2-\left(x-3\right)^2=17\)
Tự dừng bấm Gửi tl
\(\Leftrightarrow x^2+6x+9-x^2+6x-9=17\)
\(\Leftrightarrow12x=17\Leftrightarrow x=\frac{17}{12}\)
\(\frac{x+3}{x-3}-\frac{17}{x^2-9}=\frac{x-3}{x+3}\)
\(\frac{x+3}{x-3}-\frac{17}{x^2-3^2}=\frac{x-3}{x+3}\)
\(\frac{x+3}{x-3}-\frac{17}{\left(x+3\right)\left(x-3\right)}=\frac{x-3}{x+3}\)
\(\left(x+3\right)^2-17=\left(x-3\right)^2\)
\(x^2+6x-8=x^2-6x+9\)
\(6x-8=-6x+9\)
\(6x=-6x+9+8\)
\(6x+6x=17\)
\(12x=17\Leftrightarrow x=\frac{17}{12}\)
Tìm x+y biết : \(\frac{2x+1}{5}=\frac{3y-2}{7}-\frac{2x+3y-1}{6x}\)
Mình đang cần gấp mong các bạn giúp đỡ
https://olm.vn/hoi-dap/detail/233628753470.html
\(\frac{x+5}{x-5}+\frac{x-5}{x+5}=\frac{2\left(x^2+25\right)}{x^2-25}\)
mình cần gấp mong các bạn giúp đỡ
\(\frac{x+5}{x-5}+\frac{x-5}{x+5}=\frac{2\left(x^2+25\right)}{x^2-25}\left(x\ne\pm5\right)\)
\(\Leftrightarrow\frac{x+5}{x-5}+\frac{x-5}{x+5}-\frac{2\left(x^2+25\right)}{\left(x-5\right)\left(x+5\right)}=0\)
\(\Leftrightarrow\frac{\left(x+5\right)^2}{\left(x-5\right)\left(x+5\right)}+\frac{\left(x-5\right)^2}{\left(x-5\right)\left(x+5\right)}-\frac{2x^2+50}{\left(x-5\right)\left(x+5\right)}=0\)
\(\Leftrightarrow\frac{x^2+10x+25}{\left(x-5\right)\left(x+5\right)}+\frac{x^2-10x+25}{\left(x-5\right)\left(x+5\right)}-\frac{2x^2+50}{\left(x-5\right)\left(x+5\right)}=0\)
\(\Leftrightarrow\frac{x^2+10x+25+x^2-10x+25-2x^2-50}{\left(x-5\right)\left(x+5\right)}=0\)
\(\Rightarrow\frac{0}{\left(x-5\right)\left(x+5\right)}=0\)
=> PT đúng với mọi x khác \(\pm5\)
Refund QB nhìn logic :V
\(\frac{x+5}{x-5}+\frac{x-5}{x+5}=\frac{2\left(x^2+25\right)}{x^2-25}\)
\(\frac{x+5}{x-5}+\frac{x-5}{x+5}=\frac{2\left(x^2+25\right)}{\left(x+5\right)\left(x-5\right)}\)
\(\left(x+5\right)^2-\left(x-5\right)^2=2\left(x^2+25\right)\)
\(20x=2x^2+50\)
\(20x-2x^2-50=0\)
\(2\left(10x-x^2-25\right)=0\)
\(-x^2+10x+25=0\)
\(x^2-10x+25=0\)
\(x^2-2\left(x\right)\left(5\right)+5^2=0\)
\(\left(x-5\right)^2=0\)
\(x-5=0\Leftrightarrow x=5\)
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