Question

Раскройте скобки:
а) (х+1)2-(х-5)(х+5)-26+х2-2х; б) (х-2)2-(х-3)(х+3)-13

Answer 1

а)
${(x +1)}^{2} - (x - 5)(x + 5) - 26 + {x}^{2} - 2x = {x}^{2} + 2x + 1 - {x}^{2} + 25 - 26 + {x}^{2} - 2x = {x}^{2}$
б)
${(x - 2)}^{2} - (x - 3)(x + 3) - 13 = {x}^{2} - 4x + 4 - {x}^{2} + 9 - 13 = - 4x$

Answer 2

a
(x+1)^2-(x^2-25)-26+x^2-2x=(x+1)^2-x^2+25-26+x^2-2x=x^2+2x+1+25-26-2x=x^2+0=x^2

b
x^2-4x+4-(x^2-9)-13=x^2-4x+4-x^2+9-13=-4x+0=-4x