we know that
[area of rectangle]=length*width
area=2g²+34g+140
width =2g+14
step 1
find the roots of 2g²+34g+140
using a graph tool-----> to resolve the second order equation
see the attached figure
the solution is
g=-10
g=-7
so
2g²+34g+140=(2g+14)*(g+10)
therefore
the length is (g+10)
the answer is
the length is (g+10)