Question

simplifique as expressões
a) (a-2)² -2 (a+2)

b)(y+5)² - y(y+10)

c)(x-3)²+(x+3)²

d)(a-b)² -(a+b) . (a-b)

Answer 1

a) $(a-2)^{2} - 2 (a+2) \\ \\ a^{2} -4a + 4 -2a -4 \\ \\ a^{2} - 6a = a (a-6)$

b) $(y+5)^{2} -y(y+10) \\ \\ y^{2} + 10y + 25 - y^{2} -10y = 25$

c)$(x-3)^{2} + ( x+3)^{2} \\ \\ x^{2} -6x + 9 + x^{2} +6x +9 \\ \\ 2 x^{2} +18 = 2( x^{2} +9)$

d) $(a-b)^{2} -(a+b).(a-b) \\ \\ a^{2} -2ab + b^{2} - [ a^{2} - ab + ab - b^{2}] \\ \\ a^{2} -2ab + b^{2} -( a^{2} - b^{2}) \\ \\ a^{2} -2ab + b^{2}- a^{2} + b^{2} \\ \\ b^{2} - 2ab + b^{2} \\ \\ 2 b^{2} -2ab = 2b(b-a)$