(2x-3)2-(x+5).(4x-1)=-9
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H9
HT.Phong (9A5)
CTVHS
21 tháng 7 2023
1) \(9\cdot9\cdot9\cdot9\cdot3\cdot3\)
\(=3\cdot3\cdot3\cdot3\cdot3\cdot3\cdot3\cdot3\cdot3\cdot3\)
\(=3^{10}\)
2) \(8\cdot2\cdot2\cdot2\cdot16\cdot4\)
\(=2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\)
\(=2^{12}\)
3) \(3\cdot3\cdot3\cdot3\cdot5\cdot5\cdot5\cdot5\)
\(=3^4\cdot5^4\)
4) \(25\cdot25\cdot25\cdot5\)
\(=5\cdot5\cdot5\cdot5\cdot5\cdot5\cdot5\)
\(=5^7\)
5) \(7\cdot49\cdot7\cdot7\cdot7\)
\(=7\cdot7\cdot7\cdot7\cdot7\cdot7\)
\(=7^6\)
6) \(8\cdot64\cdot8\cdot64\)
\(=2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\)
\(=2^{18}\)
7) \(2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot4\)
\(=2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\cdot2\)
\(=2^8\)
TA
2
AH
Akai Haruma
Giáo viên
21 tháng 7 2023
Lời giải:
$=\sqrt{4^2}.\sqrt{5^2}+\sqrt{14^2}: \sqrt{7^2}$
$=4.5+14:7=20+2=22$
HQ
Hà Quang Minh
Giáo viên
21 tháng 7 2023
\(\left(2x-5\right)^2=\left(x-\dfrac{5}{2}\right)^2\\ \Leftrightarrow\left[{}\begin{matrix}2x-5=x-\dfrac{5}{2}\\2x-5=\dfrac{5}{2}-x\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\3x=\dfrac{15}{2}\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{5}{2}\end{matrix}\right.\\ \Leftrightarrow x=\dfrac{5}{2}\)
Vậy x = \(\dfrac{5}{2}\)
H9
HT.Phong (9A5)
CTVHS
21 tháng 7 2023
\(\left(2x-5\right)^2=\left(x-\dfrac{5}{2}\right)^2\)
\(\Leftrightarrow2x-5=x-\dfrac{5}{2}\)
\(\Leftrightarrow2x-x=-\dfrac{5}{2}+5\)
\(\Leftrightarrow x=\dfrac{5}{2}\)
DT
1
21 tháng 7 2023
\(...\Rightarrow\dfrac{20\left(x+2\right)}{360}+\dfrac{45\left(x+4\right)}{360}+\dfrac{72\left(x+5\right)}{360}=\dfrac{360\left(x+14\right)}{360}\)
\(\Rightarrow20\left(x+2\right)+45\left(x+4\right)+72\left(x+5\right)=360\left(x+14\right)\)
\(\Rightarrow20x+40+45x+180+72x+360=360x+5040\)
\(\Rightarrow137x+580=360x+5040\)
\(\Rightarrow360x-137x=5040-580\)
\(\Rightarrow223x=4460\Rightarrow x=4460:223=\dfrac{4460}{223}\)
NH
1
H9
HT.Phong (9A5)
CTVHS
21 tháng 7 2023
\(2\times3\times5+25\times8\times4+70+4\times2\times25\)
\(=15\times2+100\times8+70+100\times2\)
\(=30+800+70+200\)
\(=\left(30+70\right)+\left(800+200\right)\)
\(=100+100\times10\)
\(=100+1000\)
\(=1100\)
H9
HT.Phong (9A5)
CTVHS
21 tháng 7 2023
a) \(9^3\cdot3^2\)
\(=\left(3^2\right)^3\cdot3^2\)
\(=3^6\cdot3^2\)
\(=3^8\)
b) \(x^7\cdot x:x^4\)
\(=x^8:x^4\)
\(=x^4\)
c) \(7\cdot3^9+3^{10}+51\cdot3^8\)
\(=3^8\cdot\left(7\cdot3+3^2+51\right)\)
\(=3^8\cdot81\)
\(=3^8\cdot3^4\)
\(=3^{12}\)
d) \(5^{15}\cdot125^3\cdot625\)
\(=5^{15}\cdot5^9\cdot5^4\)
\(=5^{28}\)
NT
2
NT
1
21 tháng 7 2023
\(n.\left(n+1\right):2=210\Rightarrow n.\left(n+1\right)=210.2=420\)
Ta thấy \(20x21=420\)
\(\Rightarrow n=20\)
\(\left(2x-3\right)^2-\left(x+5\right)\left(4x-1\right)=-9\)
\(\Leftrightarrow4x^2-12x+9-4x^2+x-20x+5=-9\)
\(\Leftrightarrow-31x+14=-9\)
\(\Leftrightarrow-31x=-23\)
\(\Leftrightarrow x=\dfrac{-23}{-31}\)
\(\Leftrightarrow x=\dfrac{23}{31}\)
\(\Leftrightarrow4x^2-12x+9-4x^2+x-20x-5=-9\)
\(\Leftrightarrow31x=13\Leftrightarrow x=\dfrac{13}{31}\)