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a) x2 + 6x + 9 = x2 + 2 . x . 3 + 32 = (x + 3)2
b) 10x – 25 – x2 = -(-10x + 25 +x2) = -(25 – 10x + x2)
= -(52 – 2 . 5 . x – x2) = -(5 – x)2
c) 8x3 - 1/8 = (2x)3 – (1/2)3 = (2x - 1/2)[(2x)2 + 2x . 12 + (1/2)2]
= (2x - 1/2)(4x2 + x + 1/4)
d)1/25x2 – 64y2 = (1/5x)2(1/5x)2- (8y)2 = (1/5x + 8y)(1/5x - 8y)
a) \(a^2-2ab-15b^2=\left(a^2-2ab+b^2\right)-16a^2\)
\(=\left(a-b\right)^2-\left(4a\right)^2=\left(a-b-4a\right)\left(a-b+4a\right)=\left(-3a-b\right)\left(5a-b\right)\)
b) \(x^4+4=x^4+4x^2+4-4x^2=\left(x^2+2\right)-\left(2x\right)^2=\left(x^2-2x+2\right)\left(x^2+2x+2\right)\)
c) \(x^2-6x+8=\left(x^2-2x\right)-\left(4x-8\right)=x\left(x-2\right)-4\left(x-2\right)=\left(x-4\right)\left(x-2\right)\)
ab+b2)−16a2
=(a−b)2−(4a)2=(a−b−4a)(a−b+4a)=(−3a−b)(5a−b)
b) x4+4=x4+4x2+4−4x2=(x2+2)−(2x)2=(x2−2x+2)(x2+2x+2)
c) x2−6x+8=(x2−2x)−(4x−8)=x(x−2)−4(x−2)=(x−4)(x−2)
b )=x4-2x3-2x3+4x2+4x2-8x-8x+16
=x3(x-2)-2x2(x-2)+4x(x-2)-8(x-2)
=(x-2)(x3-2x2+4x-8)
=(x-2)[x2(x-2)+4(x-2)]
=(x-2)2(x2+4)
a) đề thiếu ko bn?
b) \(x^4-4x^3+8x^2-16x+16=\left(x^4-4x^2\right)-\left(4x^3-12x^2+8x\right)-\left(8x-16\right)\)
\(=x^2\left(x-2\right)\left(x+2\right)-4x\left(x^2-3x+2\right)-8\left(x-2\right)\)
\(=x^2\left(x-2\right)\left(x+2\right)-4x\left(x-2\right)\left(x-1\right)-8\left(x-2\right)\)
\(=\left(x-2\right)\left[x^2\left(x+2\right)-4x\left(x-1\right)-8\right]=\left(x-2\right)\left(x^3-2x^2+4x-8\right)\)
\(=\left(x-2\right)\left[\left(x^3-8\right)-\left(2x^2-4x\right)\right]=\left(x-2\right)\left[\left(x-2\right)\left(x^2+2x+4\right)-2x\left(x-2\right)\right]\)
\(=\left(x-2\right)\left(x-2\right)\left(x^2+2x+4-2x\right)=\left(x-2\right)^2\left(x^2+4\right)\)
a. `6x(x-2015)-x+2015=6x(x-2015)-(x-2015)=(x-2015)(6x-1)`
b. `x^4+4x^2+4=(x^2)^2+2.x^2 .2 +2^2=(x^2+2)^2`
a) \(6x\left(x-2015\right)-x+2015\)
\(=6x\left(x-2015\right)-\left(x-2015\right)\)
\(=\left(x-2015\right)\left(6x-1\right)\)
b) \(x^4+4x^2+4\)
\(=x^4+2\cdot x^2\cdot2+2^2\)
\(=\left(x^2+2\right)^2\)