Question

don't post irrelevant answers....!!

Answer 1

Answer:

this is your answer ✔️✔️✔️

Answer 2

Because the "y" and "x" are merely dummy variables. This is a definite integral, not an indefinite integral; the variables are only there to tell you that the function has one argument.

A definite integral is to be thought of as the "area under the graph", and so it doesn't matter what name the variable has, the area is still the same number.

∫baf(x)dx=∫baf(t)dt=∫baf

In cases when the integration is implicitly understood (for example, if there is only one variable) it is not uncommon to see the variable(s) omitted altogether, as in the last case I wrote above.