500 + x = 100 + 500

500 + x = 600

          x = 600 - 500

          x = 1001

300 - x = 300 + 200

300 - x = 500

         x = 300 - 500

         x = -200

400 - x = 200 + 400

400 - x = 600

         x = 400 - 600

         x = -200

k mk nha mk k l

ại ^_^

500 + 100 = 100 + 500

300 + 200 =  300 + 200

400 + 200  = 200 + 400

500+x=100+500

vay x =100

300-x=300+200

vay x= - 200

400-x=200+400

vay x= -200

a)1700

b)2000

a, 500+500+500+(100 x 2)

=500 x 3+ 100x2

=1500+200

=1700

b, 700+300+(100 x 10)=700+300+1000=1000+1000=2000

k minh nha

a) = 1700

b) =2000

x + 100 = 200 - 300

x + 100 = - 100

          x = 100 - 100

          x = 0

x - 300 = 400 - 500

x - 300 = -100

        x = -100 + 300

        x = 200

k mik mik k lại

x + 100 = 200 - 300

x + 100 = -100

x = -100 - 100

x = -200

x - 300 = 400 - 500

x - 300 = -100

x = -100 + 300

x = 200 

1 bang-200

2bang200

x+300=500+300

x+300=800

x=800-300

x=500

x=500+300-300

x=500

x + 300 = 500 + 300

x + 300 = 800

         x = 800 - 300

         x = 500

a)

(x - 50) : 45 + 240 = 300

(x - 50) : 45 = 60

x – 50 = 2700

x = 2750

b)

7200 : [200 + (33 600 : x) - 500] = 4

200 + (33 600 : x) – 500 = 1800

33 600 : x = 2100

x = 16

C

Chọn B nha em!

b) 200 x 4 = .800.....              300 x 2 = ..600....

200 x 2 = .400.....             300 x 3 = ...900...

400 x 2 = ...800...             500 x 1 = ..500....

100 x 4 = ..400....             100 x 3 = .300.....

800

400

800

400

600

900

500

300

ai giúp mình với

Vì |x+300|>=0, |500+x|>=0

=>|500+x|+|x+300|>=0

Nên MIN A =0

????????????????????????

Ta có: A= \(|x-500|+|x-300|\)

              =\(|x-500|+|300-x|\)

Áp dụng: \(|x|+|y|\ge|x+y|\)

\(\Rightarrow A\ge|x-500+300-x|\)

\(\Rightarrow A\ge|-200|\Leftrightarrow A\ge200\)

Để A đạt GTNN \(\Rightarrow|x-500|+|300-x|\)

\(\Leftrightarrow\)\(x-500\ge0\)                        \(\Rightarrow\)\(x\ge500\)

\(\Leftrightarrow\) \(300-x\ge0\)                        \(\Rightarrow\)\(x\le300\)
\(\Leftrightarrow\)\(x-500< 0\)                         \(\Rightarrow\)\(x>500\)

\(\Leftrightarrow\)\(300-x>0\)                         \(\Rightarrow\)\(x< 300\)

\(\Rightarrow\)\(300\le x\le500\)

Vậy A có GTNN = 200 khi và chỉ khi \(300\le x\le500\)

k mk nhé! Thank you very much!

\(A=\left|x-500\right|+\left|x-300\right|\)

\(A=\left|500-x\right|+\left|x-300\right|\ge\left|500-x+x-300\right|=200\)

Tự làm nốt nha !!

\(A=\left|x-500\right|-\left|x-300\right|=\left|x-500\right|+\left|300-x\right|\)

\(\Rightarrow A\ge\left|x-500+300-x\right|=200\)

Dấu "=" xảy ra \(\Leftrightarrow\hept{\begin{cases}x-500\ge0\\300-x\ge0\end{cases}}\)hoặc \(\hept{\begin{cases}x-500\le0\\300-x\le0\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}x\ge500\\x\le300\end{cases}}\left(vo-ly\right)\) hoặc \(\hept{\begin{cases}x\le500\\x\ge300\end{cases}}\)

Vậy minA = 200 \(\Leftrightarrow300\le x\le500\)

cảm ơn các bạn