Question

C1) phân tích thành nhân tử 

a) 4x^2 - 12xy + 9y^2

 

b) 27a^3 - 64b^3

 

c) (2a - 3b)(a + b )+ (5a - 2b)(3b - 2a) - (4a - 3b)^2

 

d) (2x - 6y)^2 - (3xy - 4)^2

 

C2) tìm x, biết

a) (2x - 3)^3 = (2x -9)(4x^2 +3)

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b)(5x - 4) = (5x - 2)(5x + 2)

Answer 1

a) 4x^2 - 12xy + 9y^2

=(2x)^2 - 2.2.3xy + (3y)^2

=(2x+3y)^2

b) 27a^3 - 64b^3

=(3a)^3 - (4b)^3

=(3a - 4b) [(3a)^2 +3a.4b +(4B)^2]

d) (2x - 6y)^2 - (3xy - 4)^2

=[ (2x - 6y)+ (3xy - 4) ] [ (2x - 6y)- (3xy - 4) ]

Answer 2

\(1,a,4x^2-12xy+9y^2\)

\(=\left(2x\right)^2-2.3.2xy+\left(3y\right)^2\)

\(=\left(2x-3y\right)^2\)

\(b,27a^3-64b^3\)

\(=\left(3a\right)^3-\left(4b\right)^3\)

\(\left(3a-4b\right)\left(9a^2+12ab+16b^2\right)\)