Question

Calcule:
a) (3+x)²

b) (x+5)²

c) (x+2)²

d) (3x+2)²

e) (5-x)²

f) (x+y).(x-y)

Answer 1

a)
= (3 + x)²
= 3² + 2.3x + x²
= 9 + 6x + x²

= x² + 6x + 9
**********************
b)
= (x + 5)²
= x² + 2.5x + 5²
= x² + 10x + 25
****************************
c)
= (x + 2)²
= x² + 2.2x + 2²
= x² + 4x + 4
**************************
d)
= (3x + 2)²
= (3x)² + 2.2.3x + 2²
= 9x² + 12x + 4
*****************************

e)
= (5 - x)²
= 5² - 2.5.x + (-x)²
= 25 - 10x + x²

= x² - 10x + 25
**************************

f)
= (x + y).(x - y)

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

= x² - xy + xy - y²

= x² - y²
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