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a) x\(^2\)+8x +15
=( x\(^2\)+3x) + ( 5x +15)
= x(x+3)+ 5 (x+3)
=(x+3) (x+5)
b)x\(^2\)-4x-12
=( x\(^2\)- 6x) +( 2x -12)
=x(x-6) + 2 (x-6)
=(x - 6) (x+2)
c)9x\(^2\)-6x-24
=(9x\(^2\)-18x)+ (12x-24)
=9x(x-2) + 12 (x -2 )
=(x-2) (9x+12)
a) \(x^2+8x+15\)
\(=x^2+8x+16-1\)
\(=\left(x^2+8x+16\right)-1\)
\(=\left(x+4\right)^2-1\)
\(=\left(x+4-1\right)\left(x+4+1\right)\)
\(=\left(x+3\right)\left(x+5\right)\)
b) \(x^2-4x-12\)
\(=x^2-4x+4-16\)
\(=\left(x^2-4x+4\right)-4^2\)
\(=\left(x-2\right)^2-4^2\)
\(=\left(x-2-4\right)\left(x-2+4\right)\)
\(=\left(x-6\right)\left(x+2\right)\)
c) \(9x^2-6x-24\)
\(=9x^2-6x+1-25\)
\(=\left(9x^2-6x+1\right)-5^2\)
\(=\left(3x-1\right)^2-5^2\)
\(=\left(3x-1-5\right)\left(3x-1+5\right)\)
\(=\left(3x-6\right)\left(3x+4\right)\)
a, x^4+6x^3+11x^2+6x+1
= x^4 + 6x^3 + 9x² + 2x² + 6x + 1
= x^4 + 9x² + 1 + 6x^3 + 2x² + 6x
= x^4 + 9x² + 1² + 2.x².3x + 2.x².1 + 2.3x.1
= (x² + 3x + 1)²
Mình làm được ý a nên tk 1 tk
\(4x^2-4x-35\) \(=\left(2x\right)^2-2.2x.1+1-36\)
\(=\left(2x-1\right)^2-6^2\)
\(=\left(2x-7\right)\left(2x+5\right)\)
\(18x^2-5x-2\) \(=\left(x-\frac{1}{2}\right)\left(x+\frac{2}{9}\right)\)
\(8x^3-26x^2+13x+5=\) \(8x^3-8x^2-18x^2+18x-5x+5\)
\(=8x^2\left(x-1\right)-18x\left(x-1\right)-5\left(x-1\right)\)
\(=\) \(\left(8x^2-18x-5\right)\left(x-1\right)\)
\(=\left(x-\frac{5}{2}\right)\left(x+\frac{1}{4}\right)\)\(\left(x-1\right)\)
Sorry nhé, mk mới lớp 6 thui.
Nên ko bit làm, mong đừng giận.
Nhưng xin tk nhé, đang thiếu sp trầm trọng.
Ai tk mk mk sẽ tk lại !
chị vào câu hỏi tương tự
kham khảo nha
chúc chị
thành công trong
học tập
8x3 - 27y3 = 23 . x3 - 33 . y3 = ( 2x )3 - ( 3y )3 = ( 2x - 3y ) [(2x)2 + 12xy + (3y)2 ].
Bài 1 :
(3xy-1/2).(4x2y-6xy2+1) = 12x3y2 - 18x2y3 + 3xy - 2x2y + 3xy2 - 1/2
Bài 4:
\(4x^2+8x+7=\left(4x^2+8x+4\right)+3=\left(2x+2\right)^2+3\ge3>0 \)
a, \(x^3+6x^2+11x+6\)
\(=x^3+3x^2+3x^2+9x+2x+6\)
\(=x^2\left(x+3\right)+3x\left(x+3\right)+2\left(x+3\right)\)
\(=\left(x+3\right)\left(x^2+3x+2\right)\)
\(=\left(x+3\right)\left(x^2+x+2x+2\right)\)
\(=\left(x+3\right)\text{[}x\left(x+1\right)+2\left(x+1\right)\text{]}\)
\(=\left(x+3\right)\left(x+1\right)\left(x+2\right)\)
b, \(2x^3+3x^2+3x+2\)
\(=2x^3+2x^2+x^2+x+2x+2\)
\(=2x^2\left(x+1\right)+x\left(x+1\right)+2\left(x+1\right)\)
\(=\left(x+1\right)\left(2x^2+x+2\right)\)
c, \(x^3-4x^2-8x+8\)
\(=x^3+2x^2-6x^2-12x+4x+8\)
\(=x^2\left(x+2\right)-6x\left(x+2\right)+4\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2-6x+4\right)\)
\(x^5+x+1\)
\(=\left(x^5-x^2\right)+\left(x^2+x+1\right)\)
\(=x^2.\left(x^3-1\right)+\left(x^2+x+1\right)\)
\(=x^2.\left(x-1\right)\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)
Đề sai nhé .Sửu lại
\(x^2-4x^2y^2+4+4x\)
\(=\left(x^2+4x+4\right)-4x^2y^2\)
\(=\left(x+2\right)^2-\left(2xy\right)^2\)
\(=\left(x+2+2xy\right)\left(x+2-2xy\right)\)
b) 4x2 -8x-5
=4x2-10x+2x-5
=2x(2x-5)+(2x-5)
=(2x-5)(2x+1)
a) 6x2 -11x -10
= 6x2 -15x +4x -10
= 3x(2x-5) + 2(2x-5)
= (2x-5)(3x+2)