Question

descompuneti in factori 9xla a2 -25

Answer 1

9x^2 - 25 = (3x-5) (3x+5) 

a^2 -b^2 = ( a-b)(a+b) 

Answer 2

$9x^2-25 = (3x)^2-5^2 = \\ \\ =\big[(3x)-5\big]\cdot \big[(3x)+5\big] =\\ \\ =(3x-5)\cdot(3x+5) \\ \\ \\ \boxed{ M-am folosit de formula: a^2+b^2 = (a-b)\cdot (a+b)}$