Question

(a+1÷13a)×(a2+1/3a2)

Answer 1

HI,
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$\frac{a+1}{13a}$*$\frac{a^2+1}{3a^2}$

= $\frac{a^3+a^2+a+1}{39a^3}$
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:-)

Answer 2

a+1/13a × a^2+1/3a^2
(a^2+1)13a=(a+1)3a^2
13a^3+13a=3a^3+3a^2
10a^3-3a^2+13a=0
a(10a^2-3a+13)=0
a(10a^2-10a-13a+13)=0
a(10a(a-1)-13(a-1))=0
a(a-1)(10a-13)=0
a=0;a=1;a=13/10