A school organized students to go to Wuxiang Temple scenic spot 6 kilometers away from the school for a spring outing. Because of something, Wang Hong couldn't take the school chartered bus, so he planned to take a taxi to Wuxiang Temple scenic spot at the school gate. Taxi fare is as follows (local price):

Within 2 kilometers (including 2 kilometers), the charge is 3.00 yuan.

For every increase of 1 km over 3 km, an additional 1.70 yuan will be charged.

(1) Write the algebraic expression of the fare paid when the taxi mileage is x km (x > 2).

(2) Wang Hong has only 10 yuan. Is she enough?

In the formula (a+ 1) 2 = a+2a+ 1, when a goes to 1, 2, 3, ..., n respectively, the following equation can be obtained.

( 1+ 1)^2= 1^2+2* 1+ 1,

(2+ 1)^2=2^2+2*2+ 1,

……

(n+ 1)^2=n^2+2n+ 1

Jiang will add the left and right sides of these equations respectively, and then the summation formula can be derived:

1+2+3+…+n= () (expressed by the relation containing n)

Supplementary question: 2 is quadratic.