Question

A, (X+1)+(x+4)+(x+7)+...+(x+25)+(x+28)=155

b,(x+9)+(x-2)+(x+7)

+(x-4)+(x+5)+(x-6)+(x+3)+(x-8)+(x+1)=95

 

Answer 1

A,(x+1)+(x+4)+(x+7)+...+(x+25)+(x+28)=155

x+1+x+4+x+7+...+x+25+x+28=155

x.[(28-1):3+1]+(1+4+7+...+25+28)=155

10.x+[(28+1).10:2]=155

10.x+145=155

Answer 2

A

<=>x+1+x+4+x+7+...+x+25+x+28=155

<=>10x.(1+4+7+10+13+16+19+22+25+28)=155

<=>10x.145  =155

<=>10x=155:145=\(\frac{31}{29}\)

x=\(\frac{31}{29}:10=\frac{31}{290}\)

Vậy x=\(\frac{31}{290}\)

Answer 3

b,

<=>x+9+x-2+x+7

<=>3x+14

Answer 4

câu nãy nhầm

<=>x+9+x-2+x+7+x-4+x+5+x-6+x+3+x-8+x+1=95

<=>9x.(9-2+7-4+5-6+3-8+1)=95

<=>9x.5=95

<=>9x=95:5=19

<=>x=19/9

Vậy x=19/9

Answer 5

B,(x+9)+(x-2)+(x+7)+(x-4)+(x+5)+(x-6)+(x+3)+(x-8)+(x+1)=95

(x+1)+(x-2)+(x+3)+(x-4)+(x-5)+(x-6)+(x+7)+(x-8)+(x+9)=95

x+1+x-2+x+3+x-4+x+5+x-6+x+7+x-8+x+9=95 

9.x+(1-2+3-4+5-6+7-8+9)=95