Nem 937 Questions 2k Answers 0 Best Answers 23 Points View Profile0 Nem Asked: Tháng Mười Một 26, 20202020-11-26T05:34:22+00:00 2020-11-26T05:34:22+00:00In: Môn ToánGiúp mk cách làm chi tiết vs !!!0Giúp mk cách làm chi tiết vs !!! ShareFacebookRelated Questions Где быстро занять денег? Một hình thang có đáy lớn là 52cm ; đáy bé kém đáy lớn 16cm ; chiều cao kém đáy ... Useful news and important articles1 AnswerOldestVotedRecentAcacia 930 Questions 2k Answers 0 Best Answers 16 Points View Profile Acacia 2020-11-26T05:36:14+00:00Added an answer on Tháng Mười Một 26, 2020 at 5:36 sáng Giải thích các bước giải:Ta có:\(\begin{array}{l}a,\\\sqrt x + \sqrt {2x} – \sqrt {4x} = \sqrt 6 – \sqrt {12} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {x \ge 0} \right)\\ \Leftrightarrow \sqrt x + \sqrt 2 .\sqrt x – 2\sqrt x = \sqrt 3 .\left( {\sqrt 2 – \sqrt 4 } \right)\\ \Leftrightarrow \left( {1 + \sqrt 2 – 2} \right).\sqrt x = \sqrt 3 \left( {\sqrt 2 – 2} \right)\\ \Leftrightarrow \left( {\sqrt 2 – 1} \right).\sqrt x = \sqrt 3 .\sqrt 2 .\left( {1 – \sqrt 2 } \right)\\ \Leftrightarrow \sqrt x = – \sqrt 6 \,\,\,\,\,\,\,\,\,\,\left( {vn} \right)\\b,\\5\sqrt {x – 2} = 10 + \sqrt {9x – 18} \,\,\,\,\,\,\,\,\,\,\left( {x \ge 2} \right)\\ \Leftrightarrow 5\sqrt {x – 2} = 10 + \sqrt {9\left( {x – 2} \right)} \\ \Leftrightarrow 5\sqrt {x – 2} = 10 + 3\sqrt {x – 2} \\ \Leftrightarrow 2\sqrt {x – 2} = 10\\ \Leftrightarrow \sqrt {x – 2} = 5\\ \Leftrightarrow x = 27\\c,\\2\sqrt {9x + 9} – 3\sqrt {x + 1} – \sqrt {4x + 4} = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {x \ge – 1} \right)\\ \Leftrightarrow 2\sqrt {9\left( {x + 1} \right)} – 3\sqrt {x + 1} – \sqrt {4\left( {x + 1} \right)} = 1\\ \Leftrightarrow 2.3.\sqrt {x + 1} – 3\sqrt {x + 1} – 2\sqrt {x + 1} = 1\\ \Leftrightarrow \sqrt {x + 1} = 1\\ \Leftrightarrow x = 0\\d,\\5\sqrt {12x} – 4\sqrt {3x} + 2\sqrt {48x} = 14\,\,\,\,\,\,\,\,\,\,\left( {x \ge 0} \right)\\ \Leftrightarrow 5.\sqrt {{2^2}.3x} – 4\sqrt {3x} + 2\sqrt {{4^2}.3x} = 14\\ \Leftrightarrow 5.2.\sqrt {3x} – 4\sqrt {3x} + 2.4\sqrt {3x} = 14\\ \Leftrightarrow 14\sqrt {3x} = 14\\ \Leftrightarrow \sqrt {3x} = 1\\ \Leftrightarrow x = \dfrac{1}{3}\\a,\\\sqrt {{{\left( {\sqrt 3 – 2} \right)}^2}} + \sqrt {12} – \sqrt {{{\left( { – 3} \right)}^2}} \\ = \left| {\sqrt 3 – 2} \right| + \sqrt {{2^2}.3} – \left| { – 3} \right|\\ = 2 – \sqrt 3 + 2\sqrt 3 – 3\\ = \sqrt 3 – 1\\b,\\3\sqrt {12} – 4\sqrt {48} + 2\sqrt {75} \\ = 3.\sqrt {{2^2}.3} – 4.\sqrt {{4^2}.3} + 2.\sqrt {{5^2}.3} \\ = 3.2.\sqrt 3 – 4.4.\sqrt 3 + 2.5.\sqrt 3 \\ = 0\\c,\\\sqrt {{{\left( {\sqrt 7 – 1} \right)}^2}} – \sqrt {28} – \sqrt {{{\left( { – 2} \right)}^4}} \\ = \left| {\sqrt 7 – 1} \right| – \sqrt {{2^2}.7} – {\left( { – 2} \right)^2}\\ = \sqrt 7 – 1 – 2\sqrt 7 – 4\\ = – \sqrt 7 – 5\\d,\\\dfrac{2}{3}\sqrt {18} – 2\sqrt 8 – \sqrt {50} + \sqrt {\dfrac{1}{2}} \\ = \dfrac{2}{3}.\sqrt {{3^2}.2} – 2\sqrt {{2^2}.2} – \sqrt {{5^2}.2} + \dfrac{1}{{\sqrt 2 }}\\ = \dfrac{2}{3}.3.\sqrt 2 – 2.2.\sqrt 2 – 5\sqrt 2 + \dfrac{{\sqrt 2 }}{2}\\ = 2\sqrt 2 – 4\sqrt 2 – 5\sqrt 2 + \dfrac{1}{2}\sqrt 2 \\ = – \dfrac{{13}}{2}\sqrt 2 \\e,\\\left( {\sqrt 8 – 3\sqrt 6 + \sqrt 2 } \right).\sqrt 2 + \sqrt {108} \\ = \left( {2\sqrt 2 – 3\sqrt 6 + \sqrt 2 } \right).\sqrt 2 + \sqrt {{6^2}.3} \\ = \left( {3\sqrt 2 – 3\sqrt 6 } \right).\sqrt 2 + 6\sqrt 3 \\ = 3.{\sqrt 2 ^2} – 3.\sqrt 6 .\sqrt 2 + 6\sqrt 3 \\ = 3.2 – 3.2.\sqrt 3 + 6\sqrt 3 \\ = 6\end{array}\)0Reply Share ShareShare on FacebookLeave an answerLeave an answerHủy By answering, you agree to the Terms of Service and Privacy Policy .* Lưu tên của tôi, email, và trang web trong trình duyệt này cho lần bình luận kế tiếp của tôi.
Acacia
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
\sqrt x + \sqrt {2x} – \sqrt {4x} = \sqrt 6 – \sqrt {12} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {x \ge 0} \right)\\
\Leftrightarrow \sqrt x + \sqrt 2 .\sqrt x – 2\sqrt x = \sqrt 3 .\left( {\sqrt 2 – \sqrt 4 } \right)\\
\Leftrightarrow \left( {1 + \sqrt 2 – 2} \right).\sqrt x = \sqrt 3 \left( {\sqrt 2 – 2} \right)\\
\Leftrightarrow \left( {\sqrt 2 – 1} \right).\sqrt x = \sqrt 3 .\sqrt 2 .\left( {1 – \sqrt 2 } \right)\\
\Leftrightarrow \sqrt x = – \sqrt 6 \,\,\,\,\,\,\,\,\,\,\left( {vn} \right)\\
b,\\
5\sqrt {x – 2} = 10 + \sqrt {9x – 18} \,\,\,\,\,\,\,\,\,\,\left( {x \ge 2} \right)\\
\Leftrightarrow 5\sqrt {x – 2} = 10 + \sqrt {9\left( {x – 2} \right)} \\
\Leftrightarrow 5\sqrt {x – 2} = 10 + 3\sqrt {x – 2} \\
\Leftrightarrow 2\sqrt {x – 2} = 10\\
\Leftrightarrow \sqrt {x – 2} = 5\\
\Leftrightarrow x = 27\\
c,\\
2\sqrt {9x + 9} – 3\sqrt {x + 1} – \sqrt {4x + 4} = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {x \ge – 1} \right)\\
\Leftrightarrow 2\sqrt {9\left( {x + 1} \right)} – 3\sqrt {x + 1} – \sqrt {4\left( {x + 1} \right)} = 1\\
\Leftrightarrow 2.3.\sqrt {x + 1} – 3\sqrt {x + 1} – 2\sqrt {x + 1} = 1\\
\Leftrightarrow \sqrt {x + 1} = 1\\
\Leftrightarrow x = 0\\
d,\\
5\sqrt {12x} – 4\sqrt {3x} + 2\sqrt {48x} = 14\,\,\,\,\,\,\,\,\,\,\left( {x \ge 0} \right)\\
\Leftrightarrow 5.\sqrt {{2^2}.3x} – 4\sqrt {3x} + 2\sqrt {{4^2}.3x} = 14\\
\Leftrightarrow 5.2.\sqrt {3x} – 4\sqrt {3x} + 2.4\sqrt {3x} = 14\\
\Leftrightarrow 14\sqrt {3x} = 14\\
\Leftrightarrow \sqrt {3x} = 1\\
\Leftrightarrow x = \dfrac{1}{3}\\
a,\\
\sqrt {{{\left( {\sqrt 3 – 2} \right)}^2}} + \sqrt {12} – \sqrt {{{\left( { – 3} \right)}^2}} \\
= \left| {\sqrt 3 – 2} \right| + \sqrt {{2^2}.3} – \left| { – 3} \right|\\
= 2 – \sqrt 3 + 2\sqrt 3 – 3\\
= \sqrt 3 – 1\\
b,\\
3\sqrt {12} – 4\sqrt {48} + 2\sqrt {75} \\
= 3.\sqrt {{2^2}.3} – 4.\sqrt {{4^2}.3} + 2.\sqrt {{5^2}.3} \\
= 3.2.\sqrt 3 – 4.4.\sqrt 3 + 2.5.\sqrt 3 \\
= 0\\
c,\\
\sqrt {{{\left( {\sqrt 7 – 1} \right)}^2}} – \sqrt {28} – \sqrt {{{\left( { – 2} \right)}^4}} \\
= \left| {\sqrt 7 – 1} \right| – \sqrt {{2^2}.7} – {\left( { – 2} \right)^2}\\
= \sqrt 7 – 1 – 2\sqrt 7 – 4\\
= – \sqrt 7 – 5\\
d,\\
\dfrac{2}{3}\sqrt {18} – 2\sqrt 8 – \sqrt {50} + \sqrt {\dfrac{1}{2}} \\
= \dfrac{2}{3}.\sqrt {{3^2}.2} – 2\sqrt {{2^2}.2} – \sqrt {{5^2}.2} + \dfrac{1}{{\sqrt 2 }}\\
= \dfrac{2}{3}.3.\sqrt 2 – 2.2.\sqrt 2 – 5\sqrt 2 + \dfrac{{\sqrt 2 }}{2}\\
= 2\sqrt 2 – 4\sqrt 2 – 5\sqrt 2 + \dfrac{1}{2}\sqrt 2 \\
= – \dfrac{{13}}{2}\sqrt 2 \\
e,\\
\left( {\sqrt 8 – 3\sqrt 6 + \sqrt 2 } \right).\sqrt 2 + \sqrt {108} \\
= \left( {2\sqrt 2 – 3\sqrt 6 + \sqrt 2 } \right).\sqrt 2 + \sqrt {{6^2}.3} \\
= \left( {3\sqrt 2 – 3\sqrt 6 } \right).\sqrt 2 + 6\sqrt 3 \\
= 3.{\sqrt 2 ^2} – 3.\sqrt 6 .\sqrt 2 + 6\sqrt 3 \\
= 3.2 – 3.2.\sqrt 3 + 6\sqrt 3 \\
= 6
\end{array}\)