Question

tìm x biết 

x²-9x+20=0

x+(x+1)+(x+2)+...+(x+2000)=0

giúp vs mn ơi mai e kiểm tra oy T_T

Answer 1

x²-9x+20=0 =>x²-5x-4x+20=0

=>x(x-5) - 4(x-5)=0

=>(x-4)(x-5)=0

=> x= {4;5}

x+(x+1)+(x+2)+...+(x+2000)=0

=> 2001x + 2001000=0

=> 2001x=-2001000

=> x=-1000

Answer 2

toán lớp 7 mà dễ quá vậy =.=

Answer 3

a)x²-9x+20=0

<=>(x-4)(x-5)=0

=>x-4=0 hoặc x-5=0

=>x=4 hoặc x=5

b)x+(x+1)+(x+2)+...+(x+2000)=0

=>(x+x+x+...+x)+(1+2+3+...+2000)=0

=>2001x+2001000=0

=>2001x=-2001000

=>x=-1000

Answer 4

a) x²-9x+20=0

<=> x²-4x-5x+20=0

<=> x(x-4)-5(x-4)=0

<=> (x-4)(x-5)=0

<=> x=4 hoặc x=5

b) x+(x+1)+(x+2)+...+(x+2000)=0

<=> 2001x+2001000=0

<=> 2001x=-2001000

<=> x=-1000

Answer 5

a)x²-9x+20=0

<=>(x-4)(x-5)=0

=>x-4=0 hoặc x-5=0

=>x=4 hoặc x=5

b)x+(x+1)+(x+2)+...+(x+2000)=0

=>(x+x+x+...+x)+(1+2+3+...+2000)=0

=>2001x+2001000=0

=>2001x=-2001000

=>x=-1000