Phân tích thành nhân tử:
\(16x^3-12x^2+3x-7\)
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12x^3+16x^2-5x-3 = 12x3+18x2 -2x2-3x -2x -3
= 12x2(x +3/2) -2x(x+3/2) -2(x+3/2)
=(12x2-2x-2)(x+3/2)
=2(6x2-x-1)(x+3/2)
=2[6x(x+1/3)-3(x+1/3)](x+3/4)
=2(6x-3)(x+1/3)(x+3/4)
=6(2x-1)(x+1/3)(x+3/4)
= (12x^3-6x^2)+(22x^2-11x)+(6x-3)
= (2x-1).(6x^2+11x+3)
= (2x-1).[(6x^2+2x)+(9x+3)]
= (2x-1).(3x+1).(2x+3)
k mk nha
Ta có: \(12x^3+16x^2-5x-3\)
\(=12x^3-6x^2+22x^2-11x+6x-3\)
\(=6x^2\left(2x-1\right)+11x\left(2x-1\right)+3\left(2x-1\right)\)
\(=\left(2x-1\right)\left(6x^2+11x+3\right)\)
\(=\left(2x-1\right)\left(6x^2+9x+2x+3\right)\)
\(=\left(2x-1\right)\left(2x+3\right)\left(3x+1\right)\)
`@` `\text {Ans}`
`\downarrow`
`x^2 + 4x + 3`
`= x^2 + 3x + x + 3`
`= (x^2 + 3x) + (x + 3)`
`= x(x + 3) + (x + 3)`
`= (x+1)(x+3)`
____
`2x^2 + 3x - 5`
`= 2x^2 + 5x - 2x - 5`
`= (2x^2 - 2x) + (5x - 5)`
`= 2x(x - 1) + 5(x - 1)`
`= (2x + 5)(x - 1)`
____
`16x - 5x^2 - 3`
`= 15x + x - 5x^2 - 3`
`= (15x - 5x^2) + (x - 3)`
`= 5x(3 - x) + (x - 3)`
`= -5x(x - 3) + (x - 3)`
`= (1 - 5x)(x - 3)`
\(-5x^2+15x+x-3\) thì phải bằng \(-5x\left(x-3\right)+\left(x-3\right)\) chứ ạ
a) Ta có: \(4x^2-28xy+49y^2\)
\(=\left(2x\right)^2-2\cdot2x\cdot7y+\left(7y\right)^2\)
\(=\left(2x-7y\right)^2\)
b) Ta có: \(x^2+8xy+16y^2\)
\(=x^2+2\cdot x\cdot4y+\left(4y\right)^2\)
\(=\left(x+4y\right)^2\)
c) Ta có: \(x^2-12x+36\)
\(=x^2-2\cdot x\cdot6+6^2\)
\(=\left(x-6\right)^2\)
7, 4x mũ 2 - 12x + 9 - y mũ 2 = -(y-2x+3) (y+2x-3)
8, 16x mũ 2 - 4y mũ 2 + 4y - 1 = -(2y - 4x - 1) (2y+4x-1)
9, 25 - x mũ 2 - 12x - 36 = -(x+1) (x+11)
10, x mũ 2 - 9 - 5 ( x + 3 ) = (x-8) (x+3)
bạn k cho mình nha
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Câu hỏi của Phạm Đỗ Bảo Ngọc - Toán lớp 8 - Học trực tuyến OLM
đa thức này đã phân tích thành nhân tử rồi bạn ạ
1) \(\left(3x^2-3y^2\right)-\left(12x-12y\right)\)
\(=3xy\left(x-y\right)-12\left(x-y\right)\)
\(=\left(3xy-12\right)\left(x-y\right)\)
2) \(4x^3+4xy^2+8x^2y-16x\)
\(=\left(4x^3-16x\right)+\left(4xy^2+8x^2y\right)\)
\(=4x\left(x^2-4\right)+4xy\left(y+2x\right)\)
Ta có : 3x2 - 3y2 - 12x + 12y
= (3x2 - 3y2) - (12x - 12y)
= 3(x2 - y2) - 12(x - y)
= 3(x - y)(x + y) - 4.3.(x - y)
= 3(x - y)(x + y - 4)
2:
a: \(x^2-12x+20\)
\(=x^2-2x-10x+20\)
=x(x-2)-10(x-2)
=(x-2)(x-10)
b: \(2x^2-x-15\)
=2x^2-6x+5x-15
=2x(x-3)+5(x-3)
=(x-3)(2x+5)
c: \(x^3-x^2+x-1\)
=x^2(x-1)+(x-1)
=(x-1)(x^2+1)
d: \(2x^3-5x-6\)
\(=2x^3-4x^2+4x^2-8x+3x-6\)
\(=2x^2\left(x-2\right)+4x\left(x-2\right)+3\left(x-2\right)\)
\(=\left(x-2\right)\left(2x^2+4x+3\right)\)
e: \(4y^4+1\)
\(=4y^4+4y^2+1-4y^2\)
\(=\left(2y^2+1\right)^2-\left(2y\right)^2\)
\(=\left(2y^2+1-2y\right)\left(2y^2+1+2y\right)\)
f; \(x^7+x^5+x^3\)
\(=x^3\left(x^4+x^2+1\right)\)
\(=x^3\left(x^4+2x^2+1-x^2\right)\)
\(=x^3\left[\left(x^2+1\right)^2-x^2\right]\)
\(=x^3\left(x^2-x+1\right)\left(x^2+x+1\right)\)
g: \(\left(x^2+x\right)^2-5\left(x^2+x\right)+6\)
\(=\left(x^2+x\right)^2-2\left(x^2+x\right)-3\left(x^2+x\right)+6\)
\(=\left(x^2+x\right)\left(x^2+x-2\right)-3\left(x^2+x-2\right)\)
\(=\left(x^2+x-2\right)\left(x^2+x-3\right)\)
\(=\left(x^2+x-3\right)\left(x+2\right)\left(x-1\right)\)
h: \(\left(x^2+2x\right)^2-2\left(x+1\right)^2-1\)
\(=\left(x^2+2x+1-1\right)^2-2\left(x+1\right)^2-1\)
\(=\left[\left(x+1\right)^2-1\right]^2-2\left(x+1\right)^2-1\)
\(=\left(x+1\right)^4-2\left(x+1\right)^2+1-2\left(x+1\right)^2-1\)
\(=\left(x+1\right)^4-4\left(x+1\right)^2\)
\(=\left(x+1\right)^2\left[\left(x+1\right)^2-4\right]\)
\(=\left(x+1\right)^2\left(x+1+2\right)\left(x+1-2\right)\)
\(=\left(x+1\right)^2\cdot\left(x+3\right)\left(x-1\right)\)
i: \(x^2+4xy+4y^2-4\left(x+2y\right)+3\)
\(=\left(x+2y\right)^2-4\left(x+2y\right)+3\)
\(=\left(x+2y\right)^2-\left(x+2y\right)-3\left(x+2y\right)+3\)
\(=\left(x+2y\right)\left(x+2y-1\right)-3\left(x+2y-1\right)\)
\(=\left(x+2y-1\right)\left(x+2y-3\right)\)
j: \(x\cdot\left(x+1\right)\left(x+2\right)\left(x+3\right)-3\)
\(=\left(x^2-3x\right)\left(x^2-3x+2\right)-3\)
\(=\left(x^2-3x\right)^2+2\left(x^2-3x\right)-3\)
\(=\left(x^2-3x+3\right)\left(x^2-3x-1\right)\)