When writing numbers in base 10, we only allow coefficients of 0 through 9. why is that?

(98 points) i need with 5 questions. answer definitions are welcomed, but not necessary.

Apolynomial function has a root of –6 with multiplicity 1, a root of –2 with multiplicity 3, a root of 0 with multiplicity 2, and a root of 4 with multiplicity 3. if the function has a positive leading coefficient and is of odd degree, which statement about the graph is true?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ac=26 and ch=8, find bh.