Question

Bài 1:

a, A=1+(-2)+(-3)+4+5+(-6)+(-7)+8+...+99-100-101+102+103

b, B=1+(-3)+5+(-7)+...+97+(-99)+101

Bài 2:

a,|x+2|-x=2

b,|x-3|+x-3=0

c, |x+1|+|x+2|=1

d,|x-5|+x-8=6

Answer 1

1

b;

B=1+ (7-5) + (11-9) + ...+(101-99)

B=1+2+2+..+2

B=1+25.2=51

Answer 2

2.

a.

ĐK : x+2 >=0 => x>=-2

\(\left|x+2\right|-x=2\\ \Rightarrow\left|x+2\right|=2+x\\ \Rightarrow\left[{}\begin{matrix}x+2=x+2\\x+2=-x-2\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}0x=0\\2x=-4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}0x=0\\x=-2\end{matrix}\right.\)

Vậy x=-2

Answer 3

2.

d;

\(\left|x-5\right|\)=14-x

\(\Leftrightarrow\left[{}\begin{matrix}x-5=14-x\\x-5=x-14\end{matrix}\right.\)

em giải 2 cái này ra để tìm x