Khánh Gia 908 Questions 2k Answers 0 Best Answers 13 Points View Profile0 Khánh Gia Asked: Tháng Mười Một 26, 20202020-11-26T04:49:42+00:00 2020-11-26T04:49:42+00:00In: Môn ToánHelp me . I love you chu cà mo ????????????????0Help me . I love you chu cà mo ???????????????? 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 articles2 AnswersOldestVotedRecentKing 908 Questions 2k Answers 0 Best Answers 29 Points View Profile King 2020-11-26T04:51:34+00:00Added an answer on Tháng Mười Một 26, 2020 at 4:51 sáng Giải thích các bước giải:Ta có:\(\begin{array}{l}a,\\\dfrac{{32}}{{{2^n}}} = 4 \Leftrightarrow {2^n} = 32:4 \Leftrightarrow {2^n} = 8 \Leftrightarrow {2^n} = {2^3} \Leftrightarrow n = 3\\b,\\\dfrac{{625}}{{{5^n}}} = 5 \Leftrightarrow {5^n} = 625:5 \Leftrightarrow {5^n} = 125 \Leftrightarrow {5^n} = {5^3} \Leftrightarrow n = 3\\c,\\{27^n}:{3^n} = 1\\ \Leftrightarrow {\left( {{3^3}} \right)^n}:{3^n} = 1\\ \Leftrightarrow {3^{3n}}:{3^n} = 1\\ \Leftrightarrow {3^{3n – n}} = 1\\ \Leftrightarrow {3^{2n}} = {3^0}\\ \Leftrightarrow 2n = 0\\ \Leftrightarrow n = 0\\4,\\\dfrac{{{4^6}{{.9}^5} + {6^9}.120}}{{{8^4}{{.3}^{12}} – {6^{11}}}}\\ = \dfrac{{{{\left( {{2^2}} \right)}^5}.{{\left( {{3^2}} \right)}^5} + {{\left( {2.3} \right)}^9}{{.2}^3}.3.5}}{{{{\left( {{2^3}} \right)}^4}{{.3}^{12}} – {{\left( {2.3} \right)}^{11}}}}\\ = \dfrac{{{2^{10}}{{.3}^{10}} + {2^9}{{.3}^9}{{.2}^3}.3.5}}{{{2^{12}}{{.3}^{12}} – {2^{11}}{{.3}^{11}}}}\\ = \dfrac{{{2^{10}}{{.3}^{10}} + {2^{12}}{{.3}^{10}}.5}}{{{2^{11}}{{.3}^{11}}.\left( {2.3 – 1} \right)}}\\ = \dfrac{{{2^{10}}{{.3}^{10}}.\left( {1 + {2^2}.5} \right)}}{{{2^{11}}{{.3}^{11}}.5}}\\ = \dfrac{{{2^{10}}{{.3}^{10}}.21}}{{{2^{11}}{{.3}^{11}}.5}}\\ = \dfrac{{21}}{{2.3.5}}\\ = \dfrac{{21}}{{30}} = \dfrac{7}{{10}}\\5,\\a,\\{x^2} – 0,25 = 0\\ \Leftrightarrow {x^2} = 0,25\\ \Leftrightarrow \left[ \begin{array}{l}x = 0,5\\x = – 0,5\end{array} \right.\\b,\\{x^3} + 27 = 0\\ \Leftrightarrow {x^3} = – 27\\ \Leftrightarrow x = – 3\\c,\\{\left( {\dfrac{1}{2}} \right)^x} = 64\\ \Leftrightarrow \dfrac{1}{{{2^x}}} = {2^6}\\ \Leftrightarrow {2^x}{.2^6} = 1\\ \Leftrightarrow {2^{x + 6}} = {2^0}\\ \Leftrightarrow x + 6 = 0\\ \Leftrightarrow x = – 6\end{array}\) 0Reply Share ShareShare on FacebookTryphena 913 Questions 2k Answers 0 Best Answers 13 Points View Profile Tryphena 2020-11-26T04:51:37+00:00Added an answer on Tháng Mười Một 26, 2020 at 4:51 sáng Đáp án: Giải thích các bước giải: bài 3:a) `32/2^n=4``⇔2^n=32/4``⇔2^n=8``⇔2^n=2^3``⇔n=3`b) `27^n:3^n=1``⇔(3^3)^n:3^n=1``⇔3^(3n):3^n=1``⇔3^(3n-n)=3^0``⇔2n=0``⇔n=0`c) `625/5^n=5``⇔5^n=625/5``⇔5^n=125``⇔5^n=5^3``⇔n=3`bài 4:`(4^6.(9^5)+6^9.(120))/(8^4.(3^12)-6^11``=((2^2)^6.(3^2)^5+(2.3)^9.(2^3).(3).5)/((2^3)^4.(3^12)-(2.3)^11)``=(2^12.(3^10)+2^12.(3^10).5)/(2^12.(3^12)-2^11(3^11))``=[2^12.(3^10)(1+5)]/[2^11.(3^11)(2.3-1)]``=(2^12.(3^10).6)/(2^11.(3^11).5)``=(2.2)/5=4/5`bài 5:`a) x^2-0,25=0``⇔x^2-1/4=0``⇔(x-1/2)(x+1/2)=0``⇔x-1/2=0` hoặc `x+1/2=0``⇔x=+-1/2``b) x^3+27=0``⇔(x+3)(x^2-3x+9)=0`do `x^2-3x+9=x^2-2.x3/2+9/4+27/4=(x-3/2)^2+27/4>=27/4>0` với mọi `x``⇒x+3=0⇔x=-3``c) (1/2)^x=64``⇔1/2^x=2^6``⇔2^6.(2^x)=1``⇔2^(6+x)=2^0``⇔6+x=0``⇔x=-6`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.
King
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
\dfrac{{32}}{{{2^n}}} = 4 \Leftrightarrow {2^n} = 32:4 \Leftrightarrow {2^n} = 8 \Leftrightarrow {2^n} = {2^3} \Leftrightarrow n = 3\\
b,\\
\dfrac{{625}}{{{5^n}}} = 5 \Leftrightarrow {5^n} = 625:5 \Leftrightarrow {5^n} = 125 \Leftrightarrow {5^n} = {5^3} \Leftrightarrow n = 3\\
c,\\
{27^n}:{3^n} = 1\\
\Leftrightarrow {\left( {{3^3}} \right)^n}:{3^n} = 1\\
\Leftrightarrow {3^{3n}}:{3^n} = 1\\
\Leftrightarrow {3^{3n – n}} = 1\\
\Leftrightarrow {3^{2n}} = {3^0}\\
\Leftrightarrow 2n = 0\\
\Leftrightarrow n = 0\\
4,\\
\dfrac{{{4^6}{{.9}^5} + {6^9}.120}}{{{8^4}{{.3}^{12}} – {6^{11}}}}\\
= \dfrac{{{{\left( {{2^2}} \right)}^5}.{{\left( {{3^2}} \right)}^5} + {{\left( {2.3} \right)}^9}{{.2}^3}.3.5}}{{{{\left( {{2^3}} \right)}^4}{{.3}^{12}} – {{\left( {2.3} \right)}^{11}}}}\\
= \dfrac{{{2^{10}}{{.3}^{10}} + {2^9}{{.3}^9}{{.2}^3}.3.5}}{{{2^{12}}{{.3}^{12}} – {2^{11}}{{.3}^{11}}}}\\
= \dfrac{{{2^{10}}{{.3}^{10}} + {2^{12}}{{.3}^{10}}.5}}{{{2^{11}}{{.3}^{11}}.\left( {2.3 – 1} \right)}}\\
= \dfrac{{{2^{10}}{{.3}^{10}}.\left( {1 + {2^2}.5} \right)}}{{{2^{11}}{{.3}^{11}}.5}}\\
= \dfrac{{{2^{10}}{{.3}^{10}}.21}}{{{2^{11}}{{.3}^{11}}.5}}\\
= \dfrac{{21}}{{2.3.5}}\\
= \dfrac{{21}}{{30}} = \dfrac{7}{{10}}\\
5,\\
a,\\
{x^2} – 0,25 = 0\\
\Leftrightarrow {x^2} = 0,25\\
\Leftrightarrow \left[ \begin{array}{l}
x = 0,5\\
x = – 0,5
\end{array} \right.\\
b,\\
{x^3} + 27 = 0\\
\Leftrightarrow {x^3} = – 27\\
\Leftrightarrow x = – 3\\
c,\\
{\left( {\dfrac{1}{2}} \right)^x} = 64\\
\Leftrightarrow \dfrac{1}{{{2^x}}} = {2^6}\\
\Leftrightarrow {2^x}{.2^6} = 1\\
\Leftrightarrow {2^{x + 6}} = {2^0}\\
\Leftrightarrow x + 6 = 0\\
\Leftrightarrow x = – 6
\end{array}\)
Tryphena
Đáp án:
Giải thích các bước giải:
bài 3:
a) `32/2^n=4`
`⇔2^n=32/4`
`⇔2^n=8`
`⇔2^n=2^3`
`⇔n=3`
b) `27^n:3^n=1`
`⇔(3^3)^n:3^n=1`
`⇔3^(3n):3^n=1`
`⇔3^(3n-n)=3^0`
`⇔2n=0`
`⇔n=0`
c) `625/5^n=5`
`⇔5^n=625/5`
`⇔5^n=125`
`⇔5^n=5^3`
`⇔n=3`
bài 4:
`(4^6.(9^5)+6^9.(120))/(8^4.(3^12)-6^11`
`=((2^2)^6.(3^2)^5+(2.3)^9.(2^3).(3).5)/((2^3)^4.(3^12)-(2.3)^11)`
`=(2^12.(3^10)+2^12.(3^10).5)/(2^12.(3^12)-2^11(3^11))`
`=[2^12.(3^10)(1+5)]/[2^11.(3^11)(2.3-1)]`
`=(2^12.(3^10).6)/(2^11.(3^11).5)`
`=(2.2)/5=4/5`
bài 5:
`a) x^2-0,25=0`
`⇔x^2-1/4=0`
`⇔(x-1/2)(x+1/2)=0`
`⇔x-1/2=0` hoặc `x+1/2=0`
`⇔x=+-1/2`
`b) x^3+27=0`
`⇔(x+3)(x^2-3x+9)=0`
do `x^2-3x+9=x^2-2.x3/2+9/4+27/4=(x-3/2)^2+27/4>=27/4>0` với mọi `x`
`⇒x+3=0⇔x=-3`
`c) (1/2)^x=64`
`⇔1/2^x=2^6`
`⇔2^6.(2^x)=1`
`⇔2^(6+x)=2^0`
`⇔6+x=0`
`⇔x=-6`