các bạn làm giúp mình luôn cái

(2x+3y)²=2x²+12xy+3y²

(5x-y)²=25x²-10xy+y²

(x+1/4)²=x²+1/2x+1/16

(1/3x-1/2y)²=1/9x²-1/3xy+1/4y²

(3x+1)(3x-1)=3x²-1

(x²+2/5y)(x²-2/5y)=x⁴-4/25y²

\(2\left(a-b\right)\left(c-b\right)+2\left(b-a\right)\left(c-a\right)+2\left(b-c\right)\left(a-c\right)\)

\(=2\left(ac-ab-bc+b^2\right)+2\left(bc-ab-ac+a^2\right)+2\left(ab-bc-ac+c^2\right)\)

\(=2ac-2ab-2bc+2b^2+2bc-2ab-2ac+2a^2+2ab-2bc-2ac+2c^2\)

\(=2a^2+2b^2+2c^2-2ab-2bc-2ac\)

\(=\left(a^2-2ab+b^2\right)+\left(b^2-2bc+c^2\right)+\left(a^2-2ac+c^2\right)\)

\(=\left(a-b\right)^2+\left(b-c\right)^2+\left(a-c\right)^2\)

Trả lời:

Để A chia hết cho B thì a - 10 = 0 <=> a = 10

Vậy để đa thức A chia hết cho đa thức B thì a = 10

Trả lời:

( x + 3 )² + ( x - 2 )² = 2x² 

<=> x² + 6x + 9 + x² - 4x + 4 = 2x² 

<=> 2x² + 2x + 13 = 2x² 

<=> 2x² + 2x + 13 - 2x² = 0

<=> 2x + 13 = 0

<=> 2x = - 13

<=> x = - 13/2

Vậy x = - 13/2 là nghiệm của pt.

Trả lời:

7x² - 7y² - 14x + 14y 

= 7 ( x² - y² - 2x + 2y )

= 7 [ ( x² - y² ) - ( 2x - 2y ) ] 

= 7 [ ( x - y )( x + y ) - 2 ( x - y ) ]

= 7 ( x - y )( x + y - 2 )

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

xy - y^2 - x + y 

= y ( x - y ) - ( x - y ) 

= ( x - y ) ( y - 1 )