Question

desenvolva os produtos notáveis e reduza os termos semelhantes :
A) (x-3) (x+3) - x(x-3y)
B) (5a+3)² +(5a-3)² - 2(a+5)
c) (2x-3)² + (x-5) (x+5) - ( x+4)²

Answer 1

A) (x-3) (x+3) - x(x-3y)
=x²+3x-3x-3²-x²-3xy
=x²+9-x²-3xy
=9-3xy
=3xy+9

B) (5a+3)² +(5a-3)² - 2(a+5)
(5a+3)² +(5a-3)²=0 - 2(a+5)
=2a+10

c) (2x-3)² + (x-5) (x+5) - ( x+4)²
2x²-12x+x²+(5x-5x-25) - (x²+8x+12)
2x²-12x+x²+5x-5x-25 - x²- 8x-12
2x²-12x+5x-5x-25 - 8x-12
2x²-12x+5x-5x-25 - 8x-12
2x²-12x-25 - 8x-12
2x²-20x-25 -12
2x²-20x-37

c) (2x-3)² + (x-5) (x+5) - ( x+4)²
[2x²-2.2x.(-3)-3²]+[x²+5x-5x-5²] - (x²+2.4x+4²)
2x²+12x+9+x²-25 - x²+2.4x+4² - x²-8x-16
2x²+12x+9+x²-25 - x²+8x+4² - x²-8x-16
2x²+x²-x²-x²=x²
12x+8x-8x=12x
9-25-16=-30
=x²+12x-30