(х+6)^2=(15-х)^2 Подскажите

Question

(х+6)^2=(15-х)^2
Подскажите

Answer 1

Х²+12х+36=225-30х+х²
42х=189
х=189/42
х=4,5

Answer 2

(x+6)^2=(15-x)^2
x^2+2*x*6+6^2=15^2-2*15*x+x^2
x^2+12x+36=225-30x+x^2
x^2+12x+36-225+30x-x^2=0
42x-189=0
42x=189
x=4,5