First grade mathematics

Suppose that after working for n years, the income in Huayu Company is x. If the income in Xiada Company is y, the units are ten thousand yuan.

Then: 1+0.02 (n-1)]}*n/2 (Arithmetic sequence calculation formula, have you learned it in the first grade of junior high school?)

y={0.5+[0.5+0.005*(2*n- 1)]}*2n/2 (1 is subtracted because the annual working experience is 0 and no money is added)

We get: x=[1+0.01n-0.01)]*n

Compared with the two equations, the y value is large, so it is beneficial to choose Xiaoda Company