Question

(5+x)² - 11 = 4 - (3+x) (3-x)

Answer 1

5^2+10x+x^2-11=4-9-x^2
10x=-5-25+11 x^2 se reduc, deoarece in suma ne dau 0
10x=-30+11
10x=-19
x=-1,9

Answer 2

$\displaystyle (5+x)^2-11=4-(3+x)(3-x) \\ 5^2+2 \cdot 5 \cdot x+x^2-11=4-9+x^2 \\ 25+10x+x^2-11=4-9+x^2 \\ 10x+x^2-x^2=4-9-25+11 \\ 10x=-19 \\ x=- \frac{19}{10}$