(7x+5)^2-5(7x+5)-14=0

Question

(7x+5)^2-5(7x+5)-14=0

Answer 1

7x+5=y
y^2-5y-14=0
по теореме Виета 
y1=7  y2=-2
7x+5=7
7x=2
x1=2/7
7x+5=-2
7x=-7
x2=-1