e. \(66.28-28.36+28.2.34-2=28\left(66-28+2.34\right)-2=28.106-2=2966\)

\(f.2+4+6+..+88+90=2\times\left(1+2+3+..+50\right)=50\times51=2550\)

g.\(\left(101-99\right)+\left(97-95\right)+..+\left(5-3\right)=2+2+..+2\left(\text{25 số 2}\right)\)

= 50

27/300=0,09

3/8=0,375

\(\frac{27}{300}=0,09\)

\(\frac{3}{8}=0,375\)

-1 J NỮA CÁC BN

hình như là = - 165 thì phải

xin tiick

Gọi số cần tìm là abcde4.Khi đảo chữ số 4 lên đầu ta có 4abcde.

Ta có: abcde4 = abcde0 +4 hay abcde x 10 +4

4abcde = 400000 + abcde

=> 400000 + abcde = abcde x 40 + 16

399984 =abcde x 39

=> abcde = 10256

Vậy số cần tìm là 102564.

Hc tốt nha em

Gọi số cần tìm là \(abcde4\)

Ta có:

\(abcde4\times4=4abcde\)

\(\Rightarrow\) \(\left(abcde\times10+4\right)\times4=400000+abcde\)

\(\Rightarrow\) \(abcde\times40+16=400000+abcde\)

\(\Rightarrow\) \(abcde\times40-abcde=400000-16\)

\(\Rightarrow\) \(abcde\times39=399984\)

\(\Rightarrow\) \(abcde=399984\div39\)

\(\Rightarrow\)\(abcde=10256\)              

Vậy số phải tìm là 102564

a,x-1/6=1/2+1/3

x-1/6=5/6

x=5/6+1/6

x=1

b, X x 2/3=3/4:9/8

Xx 2/3=2/3

X=2/3:2/3

X=1

Tìm Min à bạn?

\(Q=\left|x-2\right|+\left|x-5\right|+\left|x+1\right|\)

\(=\left|x-2\right|+\left|5-x\right|+\left|x+1\right|\)

\(=\left(\left|x-2\right|+\left|x-5\right|\right)+\left|x+1\right|\)

\(=\left(\left|2-x+5-x\right|\right)+\left|x+1\right|\)

\(=\left|3\right|+\left|x+1\right|=\left|3+x+1\right|=\left|x+4\right|\)

Mà \(\left|x+4\right|\ge0\forall x\Rightarrow MinQ=0\)

Dấu '' = '' xảy ra khi \(x+4=0\Leftrightarrow x=-4\)

\(P=\left|x+1\right|+\left|x+2\right|+\left|x+3\right|\)

\(=\left(\left|x+1+x+2\right|\right)+\left|x+3\right|\)

\(=\left(\left|2x+3\right|+\left|x+3\right|\right)\)

\(=\left|2x+3+x+3\right|\)

\(=\left|3x+6\right|\ge0\)

Dấu '' = '' xảy ra khi \(3x+6=0\Rightarrow3x=-6\Rightarrow x=-2\)

Đặt đại 1 cái tên kk

\(N=\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{100.103}\)

\(\Rightarrow3N=3\left(\frac{1}{1.4}+\frac{1}{4.7}+...+\frac{1}{100.103}\right)\)

\(\Rightarrow3N=\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{100.103}\)

\(\Rightarrow3N=\frac{1}{1}-\frac{1}{4}+...+\frac{1}{100}-\frac{1}{103}\)

\(\Rightarrow3N=\frac{1}{1}-\frac{1}{103}\)

\(\Rightarrow N=\frac{102}{103}:3\)

\(\Rightarrow N=\frac{34}{103}\)

= 786 ( 1 + 96 + 3 )

= 786 . 100

= 78600

xin tiick