Question

1) Calcule:
a) (3 + x)2
b) (x + 5)2
c) (x + y)2
d) (x + 2)?​

Answer 1

a)

= (3 + x)²

= 3² + 2.3x + x²

= 9 + 6x + x²

= x² + 6x + 9

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b)

= (x + 5)²

= x² + 2.5x + 5²

= x² + 10x + 25

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c)

= (x + 2)²

= x² + 2.2x + 2²

= x² + 4x + 4

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d)

= (3x + 2)²

= (3x)² + 2.2.3x + 2²

= 9x² + 12x + 4

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e)

= (5 - x)²

= 5² - 2.5.x + (-x)²

= 25 - 10x + x²

= x² - 10x + 25

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f)

= (x + y).(x - y)

= x.x + x.(-y) + x.y + y.(-y)

= x² - xy + xy - y²

= x² - y²

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