Решите (3 – 2x) + (4 – 3x) + (5–5x) = 12 + 7x

Question

Решите (3 – 2x) + (4 – 3x) + (5–5x) = 12 + 7x

Answer 1

12-9х+8х-6х²+20-20х+15х-15х²=12+7х
-9х+8х-6х²-20х+15х-15х²+7х=12+20-12
х-21х²=20
21х²-х-20=0
х1,2=1±√1+4*21*20/21*2=1±√1681/42=1±41/42
х1=1+41/42=1
х2=1-41/42=40/42приблезительно 1