B = x15 - 8x14 + 8x13 - 8x2 + ... - 8x2 + 8x - 5

B = x^15 - 7x^14 -x^14+7x^13+x^13-7x^12-...-x^2+7x+x-5

B = x^14(x-7) - x^14(x-7) +...+x^2(x-7)-x(x-7)+x-5

B = 7-5=2

khoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong

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Thay vào ta được:

A=−9+15x9−75x9+125

A=.....(tính như thường)

A=-424

HT

\(x^2+5x-2\)

Vì đa thức có 2 nghiệm nên có thể phân tích thành

\(\left(x+\frac{5-\sqrt{33}}{2}\right)\left(x+\frac{5+\sqrt{33}}{2}\right)\)

\(\text{Trả lời: EC = 2 . AE}\)

~ Học tốt nhé ~ 

TL

EC=2.AE

Hok tốt nhen bạn

12x-5)(4x-1)+(3x-7)(1-16x)=81

⇒48x2−32x+5−48x2+115x−7=81

⇒48x2−32x+5−48x2+115x−7=81

⇒83x=83

⇒x=1

(12x-5)(4x-1)+(3x-7)(1-16x)=81

12x ( 4x- 1) - 5(4x-1) + 3x(1-16x) -7(1-16x) =81

12x . 4x -12x - 20x + 5 + 3x - 3x. 16x - 7 + 7.16x = 81

48x^2 -12x - 20x + 5 + 3x - 48x^2 - 7 + 112x = 81

(48x^2 - 48x^2) + (112x - 12x - 20x +3x) - ( 7 - 5) =81

83x = 81 + 2

83x =83

x=1

x^2 - y^2  + 4 - 4*x

=   - ( y - x + 2 )  *( y + x - 2 )

Phân tích thành nhân tử:
x^2 - y^2 - 4x + 4
=(x^2-4x+4)-y^2
=(x-2)^2-y^2
=(x-2+y)(x-2-y)

a/6x² - 9xy

= 3x . 2x - 3x . 3y

= 3x(2x-3y)

\(b,y^2+10y+25\)

\(=y^2+5y+5y+25\)

\(=y\left(y+5\right)+5\left(y+5\right)\)

\(=\left(y+5\right)\left(y+5\right)\)

\(=\left(y+5\right)^2\)

a) Ta có: M+(5x2−2xy)=6x2+9xy−y2M+(5x2−2xy)=6x2+9xy−y2

⇔M=6x2+9xy−y2−5x2+2xy⇔M=6x2+9xy−y2−5x2+2xy

⇔M=x2+11xy−y2⇔M=x2+11xy−y2

Vậy: M=x2+11xy−y2

b) Ta có: (3xy−4y2)−N=x2−7xy+8y2(3xy−4y2)−N=x2−7xy+8y2

⇔N=3xy−4y2−x2+7xy−8y2⇔N=3xy−4y2−x2+7xy−8y2

⇔N=−x2+10xy−12y2⇔N=−x2+10xy−12y2

Vậy: N=−x2+10xy−12y2

TL

TL

a) ( 6x²-9x ) y                                                                         b) y= -5

HT