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Bài 4: Đơn giản các biểu thức sau khi bỏ dấu ngoặc
a/ (a + b - c) - (b - c + d)
= a + b - c - b +c - d
= a + (b - b) + (-c + c) - d
= a - d
b/ -(a-b+c)+(a-b+d)
= -a + b - c + a - b + d
= (-a + a) + (b - b) - c + d
= -c + d
c/ (a+b)-(-a+b-c)
= a + b + a - b + c
= 2a + c
d/ -(a+b) + (a+b+c)
= -a - b + a + b + c
= c
câu 3:
a) = a+b-c-b+c-d
=a-d
b) = -a+b-c+a-b+d
=-c+d
c)
= -a-b+a+b-c
=-c
d) a-b-c+d+a+c
=2a-b+d
Câu 4
a) \(\frac{7}{14}=\frac{-4}{-8}\)
b) \(\frac{-81}{45}=\frac{9}{-5}\)
c) \(\frac{12}{1}=\frac{-36}{-3}\)
d) \(\frac{-5}{-3}=\frac{10}{6}\)
1.a)(a + b - c) - (b - c + d)
= a + b - c - b + c - d
= ( b - b ) + ( - c + c ) + a - d
= 0 + 0 + a - d
= a - d
b) -(a -b + c) + (a - b + d)
= - a + b - c + a - b + d
= ( - a + a ) + ( b - b ) + d - c
= 0 + 0 + d - c
= d - c
c) (a + b) - (-a + b - c)
= a + b + a - b + c
= ( a + a ) + ( b - b ) + c
= 2a + 0 + c
= 2a + c
d) -(a + b) + (a + b + c)
= -a - b + a + b + c
= c
2,
a) \(315-\left(135-x\right)=215\)
\(\Rightarrow135-x=315-215\)
\(\Rightarrow135-x=100\)
\(\Rightarrow x=135-100\)
\(\Rightarrow x=35\)
b) \(x-320:32=25\cdot16\)
\(\Rightarrow x-10=5^2\cdot4^2\)
\(\Rightarrow x-10=20^2\)
\(\Rightarrow x-10=400\)
\(\Rightarrow x=410\)
c) \(3\cdot x-2018:2=23\)
\(=3\cdot x-1009=23\)
\(\Rightarrow3\cdot x=1032\)
\(\Rightarrow x=1032:3\)
\(\Rightarrow x=344\)
d) \(280-9\cdot x-x=80\)
\(\Rightarrow280-x\cdot\left(9+1\right)=80\)
\(\Rightarrow280-10\cdot x=80\)
\(\Rightarrow10\cdot x=280-80\)
\(\Rightarrow10\cdot x=200\)
\(\Rightarrow x=20\)
e) \(38\cdot x-12\cdot x-x\cdot16=40\)
\(\Rightarrow x\cdot\left(38-12-16\right)=40\)
\(\Rightarrow x\cdot10=40\)
\(\Rightarrow x=40:10\)
\(\Rightarrow x=4\)
bài 1 công thức
SCSH: ( cuối - đầu ) : khoảng cách + 1 = ?
Tổng: ( cuối + đầu ) . SCSH : 2 = ?
Hk tốt
MỌI NGƯỜI ƠI, GIÚP MÌNH ĐI. MÌNH ĐANG RẤT CẦN
rút gọn dễ :))
\(a,-a-\left(b-a-c\right)\)
\(=-a-b+a+c\)
\(=-b+c\)
\(b,-\left(a-c\right)-\left(a-b+c\right)\)
\(=-a+c-a+b-c\)
\(=-2a+b\)
\(c,-\left(a-b+c\right)-\left(a+b+c\right)\)
\(=-a+b-c-a-b-c\)
\(=-2a-2c\)
\(\text{a, x + (-30) - [95 + (-40) + (-30)]}\)
\(x+\left(-30\right)-95+40+30\)
\(=x-95+40\)
\(=x-55\)
b, a + (273 - 120) - (270 - 120)
\(=a+273-120-270+120\)
\(=a+\left(273-270\right)+\left(-120+120\right)\)
\(=a+3\)
c, b - (294 + 130) + (94 + 130)
\(=b-294-130+94+130\)
\(=b+\left(-294+94\right)+\left(-130+130\right)\)
\(=b-200\)
2. Đơn giản biểu thức sau khi bỏ ngoặc:
a, -a - (b - a - c)
\(=-a-b+a+c\)
\(=\left(-a+a\right)-b+c\)
\(=-b+c\)
b, -(a - c ) - (a - b + c)
\(=-a+c-a+b-c\)
\(=\left(-a-a\right)+\left(c-c\right)+b\)
\(=-2a+b\)
c, -( a - b + c) - (a + b + c)
\(=-a+b-c-a-b-c\)
\(=\left(-a-a\right)+\left(b-b\right)+\left(-c-c\right)\)
\(-2a+-2c\)
học tốt !!
Bài 1:
\(a,\left(a+b-c\right)-\left(b-c-d\right)\)
\(=a+b-c-b+c+d\)
\(=a+d\)
\(b,-\left(a-b+c\right)+\left(a-b+d\right)\)
\(=-a+b-c+a-b+d\)
\(=-c+d\)
\(c,\left(a+b\right)-\left(-a+b-c\right)\)
\(=a+b+a-b+c\)
\(=2a+c\)
\(d,-\left(a+b\right)+\left(a+b+c\right)\)
\(=-a-b+a+b+c\)
\(=c\)
Bài 3 :
\(a,15-\left(4-x\right)=6\)
\(4-x=15-6\)
\(4-x=9\)
\(x=4-9\)
\(x=-5\)
\(b,-30+\left(25-x\right)=-1\)
\(25-x=-1+30\)
\(25-x=29\)
\(x=25-29\)
\(x=-4\)
\(c,x-5=-1\)
\(x=-1+5\)
\(x=4\)
\(d,x-4=-10\)
\(x=-10+4\)
\(x=-6\)
\(e,x+3=-8\)
\(x=-8-3\)
\(x=-11\)
\(g,x+6=0\)
\(x=-6\)
Câu 1:
A, (a+b-c)-(b-c-d)
= a+b-c-b+c+d
= a+(b-b)+(c-c)
= a
B, -(a-b+c)+(a-b+d)
= -a+b-c+a+b+d
= (a-a)+(b+b)+d-c
= 2b+d-c
C, (a+b)-(-a+b-c)
= a+b+a-b+c
= (a+a)+(b-b)+c
= 2a+c
D, -(a+b)+(a+b+c)
= -a-b+a+b+c
= (-a+a)+(b-b)+c
= c
=