Question

Solutia ecuatie (x-5)(x+5)-(x-3)²=x-9 este:
A. 5 B. 3 C. -5 D. -1

Answer 1

$\displaystyle (x-5)(x+5)-(x-3)^2=x-9 \\ x^2-25-(x^2-2 \cdot x \cdot 3+3^2)=x-9 \\ x^2-25-(x^2-6x+9)=x-9 \\ x^2-25-x^2+6x-9=x-9 \\ x^2-x^2+6x-x=-9+25+9 \\ 5x=25 \\ x= \frac{25}{5} \\ x=5~(A)$