Question

(2-x) la puterea 2 +(x×3) la puterea 2 -5=2(x+1)(x-1)+3

Answer 1

Buna!
(2-x)^2 + (x*3)^2 - 5 = 2(x+1)(x-1) + 3 <=>
<=> 4 + x^2 - 4*x + 9 * (x^2) - 5 = 2* (x^2 -1 ) + 3 <=>
<=> -1 -4*x + 9*(x^2) = 2*(x^2) +1 <=>
<=> 7*(x^2)=2+4*x <=>
<=> 7*(x^2) - 4*x -2=0 , care e ecuatie de gradul 2, deci avem de calculat delta.
delta = 16+4*2*7=16+56=72 , deci x1 = (4 + (6 radical din 2))/14=(2+(3 radical din 2))/7 si x2 = (4- (6 radical din 2))/14 = (2 - (3 radical din 2))/7