Question

Bài 1: Chứng minh đẳng thức:

a)-2(a-b+c)-3(b-c+a)-4(c-a+b) = -a-(a+b)-(4b+3c)

b)-3[a-(-b+c)]-[-(c-a)+(-b-a)] = 4c-3a-2b

Bài 2: Tìm x:

a)-3(x-2)-5(-x+1) = -(-x+3)

b)x-[1-x+(-x)-(3-x)] = 2[x-2(x-1)]

c)-.3{x-(-x+1)-[-z+(3-x)]} = 5-[-(-x)]

Bài 3: Tìm x,y thuộc Z biết:

xy-y = 3

Answer 1

Câu 2: 

a: \(\Leftrightarrow-3x+6+5x-5=x-3\)

=>2x+1=x-3

hay x=-4

b: \(\Leftrightarrow x-\left[1-x-x-3+x\right]=2\left[x-2x+2\right]\)

\(\Leftrightarrow x-\left(-x-2\right)=2\left(-x+2\right)\)

=>2x+2=-2x+4

=>4x=2

hay x=1/2

c: \(\Leftrightarrow-3\left\{x+x-1-\left[-x+3-x\right]\right\}=5-\left[x\right]\)

\(\Leftrightarrow-3\left\{2x+1+2x-3\right\}=5-x\)

=>-3(4x-2)=5-x

=>-12x+6=5-x

=>-11x=-1

hay x=1/11