-7x^11 is the answer.
One way that personally helps me remember the exponents properties is to imagine it written out with multiplication:
x^4 is the same as
x*x*x*x
And raised to 2 is the times itself a total of 2 times
(x*x*x*x) (x*x*x*x)
For a total of x^8. Or in other words, we can say we can “distribute” the double exponents.
x^8 times x^3 is
(x*x*x*x*x*x*x*x) * (x*x*x)
There are a total of 11 x’s or x^11
Another property when exponents are multiplied together is that they are added.
so
x^8 * -7 * x
is the same as
x^8 * x^3 * -7
And the answer is
x^11 * -7 =
-7x^11
Hope this helps