∵y=-3/5x^2+3x+ 1
Parabolic symmetry axis =-[3÷(-3/5×2)]
=3×5/6
=5/2 (2.5)
When x=5/2, y= 19/4m.
Note: It is too much trouble to solve this problem by matching method. It is best to find the value of x when y is maximum by finding the parabola symmetry axis. It's OK to bring X in! !
The second question: When x=4, just y=3.4, then the performance can be successful.
Sorry, I'm doing the problem, too. I only wrote the general process of your question. ..