a: 39870:123=324 dư 6

b: 30395:217=140 dư 15

c: 25863:250=103,452

c)\(\Leftrightarrow5x\left(x-3\right)-\left(x-3\right)=0\Leftrightarrow\left(5x-1\right)\left(x-3\right)=0\)

đến đây tự làm

a, <=> x.(x^2-4x+4) = 0

<=> x.(x-2)^2 = 0

<=> x=0 hoặc x-2=0

<=> x=0 hoặc x=2

b, <=> 5x^2-11x = -2

<=>5x^2-11x+2 =  0

<=>(5x^2-10x)-(x-2)=0

<=> (x-2).(5x-1)=0

<=>x-2=0 hoặc 5x-1=0

<=> x=2 hoặc x=1/5

c, <=> 5x.(x-3)-(x-3)=0

<=>(x-3).(5x-1)=0

<=> x-3=0 hoặc 5x-1 = 0

<=> x=3 hoặc x=1/5

k mk nha

a. x=0 hoặc x=2

b. x=1/5 hoặc x=2

c. x=3 hoặc x=1/5

217 x 45 + 50 x 217 + 217 x 5

= 217 x (45 + 50 + 5)

= 217 x 100

= 21 700

217 + [43 + (–217) + (–23)]

= 217 + 43 + (–217) + (–23)

= [217 + (–217)] + [43 + (–23)]

= 0 + 20 = 20.

217 + [ 43 + (–217) +(–23)].

   217+[43+(-217)+(-23)]

=[217+(-217)]+[43+(-23)]

=0+20

=20

Ta có:\(217+\left[43+\left(-217\right)+\left(-23\right)\right]\)

\(=217+43-217-23\)

\(=43-23\)

\(=20\)

217+[43+(-217)+(-23)]

=[217+(-217)]+[43+(-23)]

=43-23

=20

1. 2000/1000 = 2

a) 217 x 11

= 217 x (10 +1)

= 217 x 10 + 217 x 1

= 2170 + 217 = 2387

217 x 9 = 217 x (10-1)

= 217 x 10 - 217 x 1

= 2170 - 217 = 1953

b) 413 x 21 = 413 x (20 + 1)

= 413 x 20 + 413 x 1 = 8673

413 x 19 = 413 x (20-1)

= 413 x 20 - 413 x 1 = 7847

c) 1234 x 31 = 1234 x (30 +1)

= 1234 x 30+ 1234 x 1

= 37020 + 1234 = 38254

875 x 29 = 875 x (30 -1)

= 875 x 30 - 875 x 1

= 26250 - 875 = 25375