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\(445-52+155+452\\ =\left(445+155\right)+\left(452-52\right)\\ =600+4000\\ =1000\\ 102\cdot55-102\cdot73+51\cdot36\\ =102\cdot\left(55-73\right)+51\cdot36\\ =102\cdot\left(-18\right)+102\cdot18\\ =0\\ 4\cdot5\cdot2\cdot25\cdot5-1000\\ =5000-1000\\ =4000\\ 8782-291\cdot13\\ =4999\\ 254+\left\{38\cdot\left[\left(42-16\right):2\right]\right\}\\ =254+\left[38\cdot\left(26:2\right)\right]\\ =254+\left(38\cdot13\right)\\ =748\\ \left(2791\cdot34+7882:14\right)\cdot0+1510-510:2\\ =1510-255\\ =1255\)
a. \(445-52+155+452=\left(445+155\right)+\left(452-52\right)=600+400=1000\)
b. \(102\cdot55-102\cdot73+51\cdot36=102\left(55-73+18\right)=102\cdot0=0\)
c.\(4\cdot5\cdot2\cdot25\cdot5-1000=4\cdot25\cdot5\cdot5\cdot2-1000=100\cdot50-1000=5000-1000=4000\)
d. \(8782-291\cdot13=8782-3783=4999\)
e. \(254+\left\{38\left[\left(42-16\right)\div2\right]\right\}=254+\left\{30\cdot13\right\}=254+494=748\)
f. \(\left(2791\cdot34+7882\div14\right)\cdot0+1510-510\div2=0+1510-255=1255\)\
\(x\left(x+y+z\right)=10\) (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...
Bài 1 tìm x
A, (19..x+2..52)..14= (13-18)-42
B, 2..3x= 10..312+8..274
Dấu chấm có nghĩa là dấu nhân!!
(-123) + (-18) = - 141
(-375) + 210 = - 165
(-127) + 25 + (-136) = - 238
(-123)+(-18)=-(123+18)=-141
(-375)+210=210-375=-165
(-127)+25+(-136)=-127-136+25=-238
425 : 25 + 2 . x = 35
17 + 2 . x = 35
2x = 35 - 17
2x = 18
x = 18 : 2
x = 9
x - 4867 = (175 . 2 - 5 . 70): 25 .23
x - 4867 = ( 52.7.2 - 52.7.2) : 25.23
x - 4867 = 0 : 25 . 23 = 0
x = 0 + 4867
x=4867.
\(725:25.10-432:18+127=\left(725:25\right).10-\left(432:18\right)+127=29.10-24+127=290-24+127=393\)