Question

Please help and show the work please!!

Answer 1

39 - B. 31.4

40 - C. 9.8x+1.1y+9.9z

For 39, the formula for the circumference of a circle is
`2\pi r` where r is the radius of the circle. Substituting r=5 gives
`2\pi 5=31.4`.

For 40, you basically just add up like terms according to which variable the coefficient is in front of.

`5.5x+4.3x=9.8x\\6.2y-5.1y=1.1y\\8.3z+1.6z=9.9z\\9.8x+1.1y+9.9z`

Hope this helps.