Could someone help me this problem Thanks and please include

Could someone help me this problem? Thanks, and please include your steps, I have calculated several times, and couldnt get it right.

Solution

So, he wants us to get the value of x when the value of expenditures is 7000,

i.e. E = 7000 , i.e. 7000 = 7.94x^2 + 33.2x +2190

i.e. 7.94x^2 +33.2x -4810 =0

Solving this quadratic equation, we get the roots of x as x= 22.6 and x =-26.79

As x cannot be negative, the negative value is neglected.

So, x is 22.6 i.e. after 22.6 years past 2005 , the expenditures will cross 7000 billion,

and as we know that after 22 years past 2005, the expenditures will be less than 7000 billion but for the 23rd year it will cross 7000 billion dollars, so the year in which the total expenditures will cross 7000 billion dollars is (2005+ 23=) 2028