Question

Calcule mentalmente.
a) (1–10x)²
b) (5x–1) (x+3)
c) (–6x)²
d) (x+6) (x–6)
e) (a–b) (a+b)
f) 4x (x+2)²

Answer 1

( 1 - 10 x )²
( 1 - 10 x ) ( 1 - 10 x )
1 - 10 x + 100 x²
_____________
( 5 x - 1 ) ( x + 3 )
5 x² + 15 x - x - 3
5 x² + 14 x - 3
_____________
( - 6 x )²
( - 6 x ) ( - 6 x )
12 x²
_____________
( x + 6 ) ( x - 6 )
x² - 6 x + 6 x - 36
x² - 36
_____________
( a - b ) ( a + b )
a² + ab - ab - b²
a² - b²
_____________
4 x ( x + 2 ) ( x + 2 )
4 x ( x² + 2 x + 2 x + 4 )
4 x³ + 8 x² + 8 x² + 16 x
4 x³ +16 x² + 16 x