25 x 2 + 25 x 3 + 25 x 4 + 25

= 25 x (2 + 3 + 4 + 1)

= 25 x 10

= 250

**** cho mình nhé >_<

25x2+25x3+25x4+25

= 25 × 2 + 25 × 3 + 25 × 4 + 25 × 1

= 25 × ( 2 + 3 + 4 + 1 )

= 25 × 10

= 250

Nếu mình đúng thì các bạn k mình nhé

25*2+25*3+25*4+25

=25*2+25*3+25+4+25*1

=25*(2+3+4+1)

=25*10

=250

các bạn nha 

20x4y - 25x2y2 - 3x2y = 5x2y . (4x2 - 5y - 3/5)

Nên (20x4y - 25x2y2 - 3x2y) : 5x2y = 4x2 - 5y - 3/5

a: =-29x100=-2900

b: \(=\left(215-5\cdot80+5\cdot50+60\right):53=\dfrac{125}{53}\)

a: =-29x(165-65)=-29x100=-2900

b: \(=\left[215-5\cdot30-60\right]:53=0\)

\(x^2-25=\left(x-5\right)\left(x+5\right)\\ x^2+10x+25=\left(x+5\right)^2\\ x^2-6x+xy-6y=x\left(x-6\right)+y\left(x-6\right)=\left(x+y\right)\left(x-6\right)\\ x^2-2x-y^2+1=\left(x-1\right)^2-y^2=\left(x-y-1\right)\left(x+y-1\right)\)

\(A=1-25x^2-10x\)

\(=-\left(25x^2+10x-1\right)\)

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

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

A = 1 - 25x^2 - 10x = - ( 25x^2 + 10x - 1 )

= - [ ( 5x + 1 ) ^ 2 - 2 ]

= 2 - ( 5x + 1 ) ^2

Lời giải:

$M=(x^{10}-24x^9)-(x^9-24x^8)+(x^8-24x^7)-(x^7-24x^6)+(x^6-24x^5)-(x^5-24x^4)+(x^4-24x^3)-(x^3-24x^2)+(x^2-24x)-(x-24)+1$

$=x^9(x-24)-x^8(x-24)+x^7(x-24)-.....+x(x-24)-(x-24)+1$

$=(x-24)(x^9-x^8+x^7-...+x-1)+1$

$=0.(x^9-x^8+....+x-1)+1=1$

\(B=25x^2-2xy+\dfrac{1}{25}y^2=\left(5x\right)^2-2.5x.\dfrac{1}{5}y+\left(\dfrac{1}{5}y\right)^2\)

\(=\left(5x-\dfrac{1}{5}y\right)^2\)

Thay x = -1/5 ; y = -5 ta được : \(\left(-1+1\right)^2=0\)