(x-5) (x+5) - (x-3) ²=x-9

Răspuns :

(x-5)(x+5)-(x-3)²=x-9
x²-5²-x²-2·3x+3²=x-9
-6x-x=-9+5+2-9
-7x=-11
x=-11/-7
x=1  -4/7