## Solution.
Let's rewrite the equation as 35x+7=35x−12+1 and cube both sides:
5x+7=5x−12+3(35x−12)2+335x−12+1⇔⇔(35x−12)2+35x−12−6=0
Let 35x−12=t. The equation in terms of t becomes t2−t−6=0, from which we find t1=−3 and t2=2.
Then either 35x−12=−3,5x−12=−27,x1=−3, or 35x−12=2, 5x−12=8,x2=4.
Answer: x1=−3,x2=4.