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1/\(\left(x-y-z\right)-\left(2x+y+z\right)+\)\(\left(2z-2y\right)=x-y-z-2x-y-z+2z-2y\)
\(\left(x-2x\right)+\left(-y-y-2y\right)+\left(-z-z+2z\right)=-x-4y\)
2/\(\left(m-n-p\right)-\left(-m+n-p\right)-\left(n+m\right)=m-n-p+m-n+p-n-m\)
\(=\left(m+m-m\right)+\left(-n-n-n\right)+\left(-p+p\right)=-m-3n\)
3/\(\left(2a+b+c\right)-\left(b+2a+c\right)-\left(2c+b\right)=2a+b+c-b-2a-c-2c-b\)
\(=\left(2a-2a\right)+\left(b-b-b\right)+\left(c-c-2c\right)=-b-2c\)
B1:Tìm x,biết
a)\(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
\(\Leftrightarrow\left(x-3\right)7=\left(x+5\right)5\)
\(\Leftrightarrow7x-21=5x+25\)
\(\Leftrightarrow7x-21-5x-25=0\)
\(\Leftrightarrow2x-46=0\)
\(\Leftrightarrow2x=46\)
\(\Leftrightarrow x=23\)
b)\(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)
\(\Leftrightarrow7.9=\left(x-1\right)\left(x+1\right)\)
\(\Leftrightarrow63=x^2-1\)
\(\Leftrightarrow x^2=64\)
\(\Leftrightarrow x=\sqrt{64}=8\)
c)\(\dfrac{x+4}{20}=\dfrac{5}{x+4}\)
\(\Leftrightarrow\left(x+4\right)\left(x+4\right)=20.5\)
\(\Leftrightarrow\left(x+4\right)^2-100=0\)
\(\Leftrightarrow\left(x+4\right)^2-10^2=0\)
\(\Leftrightarrow\left(x+4-10\right)\left(x+4+10\right)=0\)
\(\Leftrightarrow\left(x-6\right)\left(x+14\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-6=0\\x+14=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-14\end{matrix}\right.\)
\(a.\left(-x+y\right)-\left(z+y-x\right)=-x+y-z-y+x=-z\)
\(b.\left(a-b\right)-\left(x-b+a\right)=a-b-x+b-a=-x\)
Các câu còn lại tương tự
1. Bỏ ngoặc rồi tính:
a, ( x - 1)-(x - 3)
= x - 1 - x + 3
= -1 + 3 = 2
b, (2 + y) - ( y + 1)
= 2 + y - y - 1
= 2 - 1 = 1
c,- x -( y - x - z)
= -x - y + x + z
= -y + z
d, x- z - ( x - y + z)
= x - z - x + y - z
= -2z + y
Ticks mình nhé!
a, \(\left(-a\right)\left(b-c-d\right)=-ab+ac+ad\)
b, \(x\left(y-z-2\right)=xy-xz-2x\)
c, \(\left(-3\right)\left(2x-5\right)=-6x+15\)
a/ 38+59-148-38+59=(38-38) + (59+59) -148=118-148=-30
b/43-245+69-43-69=(43-43)-245+(69-69)=-245
c/ {1260+420-620}-1260-420-280=1260+420-620-1260-420-280=(1260-1260)+(420-420)-(620+280)=-900
tạm bài 1 vì fải đi ngủ rùi
1) -(a+b-c)+(-2a+b-c-d)-(a+c-b-d)
=(-a)-b+c+(-2a)+b-c-d-a-c+b+d
=-a+(-2a)-c+b
=(-3a)-c+b
học tốt nha !!!!!!!!
1)a - b + c -2a +b-c-d - a-c+b+d
2)m- n+z+d - a+ 2c -d +z -5x +6-y +10
Ủng hộ nha