Q Find all older derivatives
y = X^4/2 = 3/2X^2 -X
y4 = 2X^2 - 3 x ^ 1 - 0
y4 = 4X^1 - 3 -0
y4 = 7
thats not so much a question as it is random keystrokes... ;)
Do you mean y = (1/2)x4 - (3/2)x2 - x?
What is y4 supposed to be? Since you have taken the derivative, this should be y'. Of the three terms you differentiated on the right side, only one is correct: d/dx[-(3/2)x2] = -3x. The other two terms have errors.
Separate names with a comma.