Question

viết bt sau dưới dạng tích:

a^2-6x+9

1-4x+4x^2

(a+b)^2-1

4x^2-9

25x^2-20xy+4y^2

Answer 1

a² - 6a + 9 = (a-3)²

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1-4x+4x² = (1-2x)²

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(a+b)² - 1 = (a+b-1)(a+b+1)

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4x²- 9 = (2x-3)(2x+3)

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25x² - 20xy + 4y² = (5x - 2y)²

Answer 2

\(4x^2-9=\left(2x\right)^2-3^2=\left(2x-3\right)\times\left(2x+3\right)\)

Answer 3

\(25x^2-20xy+4y^2=\left(5x\right)^2-2\times5x\times2y+\left(2y\right)^2=\left(5x-2y\right)^2\)

Answer 4

a^2+9-6a

Answer 5

a\(^2\)-6a+9=a\(^2\)-3a-3a+9=a\(\times\)(a-3)-3\(\times\)(a-3)=(a-3)\(\times\)(a-3)=(a-3)\(^2\)

Answer 6

\(1-4x+4x^2\)\(=\)\(\left(2x\right)^2-2\times2x\times1+1^2\)\(=\left(2x-1\right)^2\)

Answer 7

\(\left(a+b\right)^2-1=\left(a+b-1\right)\times\left(a+b+1\right)\)