Question

Can someone tell me how you get the 78.4 in this problem. C"(x)=(1.6(x^2+49)^-1/2-1)
=78.4/(x^2+49)^3/2

Answer 1

\[C"(x)=\frac{1.6}{\sqrt{x^2+49}}-1\]

Answer 2

Is that the problem?

Answer 3

I just don't understand how you get the 78.4. The problem says Find the sign of C"(5.6).
C"(x)=(1.6(x^2+49)^-1/2-1)'
=78.4/(x^2+49)^3/2

C"(5.6)=78.4/((5.6)^2+49)^3/2

Answer 4

And I cannot tell where the 78.4 came from unless I know what the original problem is. So I guess we're at a Mexican stand off as the expression goes. I can't answer your question until you answer mine and you don't want to answer mine. Sorry.

Answer 5

I don't know why but 1.6x49=78.4