Question

a) (x-1) ( x+1)= b) ( x+2) (x-2)= c) ( x+3) ( x-3)= d) (5-×) ( x+5)= e) (2x +1) (x+2)= f) ( 1-x) (5x-4)=​

Answer 1

Răspuns:

a)

$( x - 1)(x + 1) = {x}^{2} - {1}^{2} = {x}^{2} - 1$

b)

$(x + 2)(x - 2) = {x}^{2} - {2}^{2} = {x}^{2} - 4$

c)

$(x + 3)(x - 3) = {x}^{2} - {3}^{2} = {x}^{2} - 9$

d)

$(5 - x)(x + 5) = {5}^{2} - {x}^{2} = 25 - {x}^{2}$

e)

$(2x + 1)(x + 2) = 2x(x + 2) + 1(x + 2) = 2 {x}^{2} + 4x + x + 2 = 2 {x}^{2} + 5x + 2$

f)

$(1 - x)(5 x - 4) = 1(5x - 4) - x(5x - 4) = 5x - 4 - 5 {x}^{2} - 4x = 5 {x}^{2} - x - 4$

Answer 2

Răspuns:

a) (x-1)(x+1)=x^(2)-1

b) (x+2)(x-2)=x^(2)-2^(2)=x^(2)-4

c)(x+3)(x-3)=x^(2)-9

3^(2)=9

d) (5-x)(x+5)=(5-x)(5+x)=5^(2)+x^(2)=25-x^(2)

adunarea este comutativă 5+x=x+5

e) =2x^(2)+4x+x+2=2x^(2)+5x+2

f) =5x-4- 5x^(2)+4x= -5x^(2)+9x-4

Explicație pas cu pas:

La a),b),c),d) folosim (a+b)(a-b)=a^(2)-b^(2)