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\(2014.2013.2013.2012.x=2011.2012.2013.2014\)
\(\Rightarrow x=\dfrac{2011.2012.2013.2014}{2014.2013.2013.2012}\)
\(\Rightarrow x=\dfrac{2011}{2013}\)
Bạn xem lại đề
\(56.\left(15+23\right)-15.\left(23+56\right)\)
\(=\left(56.15+56.23\right)-\left(15.23+15.56\right)\)
\(=56.15+56.23-15.23-15.56\)
\(=\left(56.15-56.15\right)+\left(56.23-15.23\right)\)
\(=0.\left[23.\left(56-15\right)\right]\)
\(=23.41\)
\(=943\)
a) 56.[ 15 + 23 ] - 15.[ 23 + 56 ]
= 56. 38 - 15. 79
= 2128 - 1185
= 943
b) 12.[ 47 - 23 ] + 23. [12 + 47]
= 12 . 24 + 23. 59
= 288 + 1357
= 1645
~ chúc bạn hok tốt nha ~ ^_^
Ta có: \(1-\frac{1}{2}.\frac{2}{3}....\frac{98}{99}\)
= \(1-\frac{1}{99}\)
= \(\frac{98}{99}\)
P=\(1-\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right).........\left(1-\frac{1}{99}\right)\)
P=\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.........\frac{98}{99}=\frac{1}{99}\)
Vì \(\frac{19^{30}+5}{19^{31}+5}< 1\); \(\frac{19^{31}+5}{19^{30}+5}>1\)
Nên A < B
29.31+66.69+31.37
=31.(29+37)+66.69
=31.66+66.69
=66.(31+69)
=66.100
=6600
29.31+66.69+31 . 37
=31 . (29 + 37 ) + 66 . 69
= 31 . 66 + 66 . 69
= 66 . ( 31 + 69 )
= 66 . 100
=6600
k mink nha !
\(x\left(x+y+z\right)=10\) (1)
\(y\left(y+z+x\right)=25\) (2)
\(z\left(z+x+y\right)=-10\) (3)
Lấy (1) + (2) + (3) theo vế ta có:
\(x\left(x+y+z\right)+y\left(y+z+x\right)+z\left(z+x+y\right)=10+25-10\)
\(\Leftrightarrow\)\(\left(x+y+z\right)^2=25\)
\(\Leftrightarrow\)\(x+y+z=\pm\sqrt{25}=\pm5\)
Nếu \(x+y+z=5\) thì: \(\hept{\begin{cases}x=2\\y=5\\z=-2\end{cases}}\)
Nếu \(x+y+z=-5\)thì \(\hept{\begin{cases}x=-2\\y=-5\\z=2\end{cases}}\)
Vậy...
Ư(6)={1;2;3;6}
Voi x +3=1=≫x=1-3=-2
Voi x+3=2=≫x=2-3=-1
Voi x+3=3=≫x=3-3=0
Voi x+3=6=≫x=6-3=3
Vi 10 la boi cua 2x+5=≫2x+5 la uoc cua 10=≫ Ư(10={1;2;5;10}
Voi 2x+5=1=≫2x=1-5=-4=≫x=4÷2=2
Voi 2x+5=2=≫ 2x=2-5=-3=≫x=-3÷2= -1,5
Voi 2x+5=5=≫5-5=0=≫x=0÷2=0
Voi 2x+5=10=≫2x=10-5=5=≫x=5÷2=2,5
x3.y3=(x.y)3
2.3.8.12.24=2.3.23.3.22.23.3=29.33