\(\left(1+x\right)+\left(2+x\right)+\left(3+x\right)+\)\(\left(4+x\right)+\left(5+x\right)=10\times5\)

\(\left(1+2+3+4+5\right)+\left(x+x+x+x+x\right)=50\)

\(15+5x=50\)

\(5x=35\)

\(x=7\)

Vậy \(x=7\)

\(\left(1+x\right)+\left(2+x\right)+\left(3+x\right)+\left(4+x\right)+\left(5+x\right)=10\times5\)

\(\Rightarrow1+x+2+x+3+x+4+x+5+x=50\)

\(\Rightarrow\left(1+2+3+4+5\right)+\left(x+x+x+x+x\right)=50\)

\(\Rightarrow15+5x=50\)

\(\Rightarrow5x=50-15\)

\(\Rightarrow5x=35\)

\(\Rightarrow x=35:5\)

\(\Rightarrow x=7\).

(8 x 18 - 5 x 18 - 18 x 3)x + 2x = 8 x 7 + 24

<=> [18 x (8 - 5 - 3)]x + 2x =   80

<=> 2x = 80

<=> x = 40,k nhé bạn

(8x18-5x18-18x3)xX+2xX=8x7+24

=>8x(8-5-3)xX+2xX=80

=>8x0xX+2xX=80

=>0+2xX=80

=>X=80:2

=>X=40

A

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B __|_____\C

\(x\times x-5+x:x=12\)

\(\Rightarrow x\times x-5+1=12\)

\(\Rightarrow x\times x=12+5-1\)

\(\Rightarrow x\times x=17-1\)

\(\Rightarrow x\times x=16\)

\(\Rightarrow x\times x=4\times4\)

\(\Rightarrow x=4\).

\(x\times5-x:x-x=15\)

\(\Rightarrow x\times5-1-x=15\)

\(\Rightarrow x\times5-x=15+1\)

\(\Rightarrow x\times\left(5-1\right)=16\)

\(\Rightarrow x\times4=16\)

\(\Rightarrow x=16:4\)

\(\Rightarrow x=4\).

Cần lấy ra ít nhất số bi để chắc chắn ó 4 màu viên bi khác nhau là:

3+3+3+3+1=15 viên

đ/s:.....