Maths !

bonkysleuth SG

Light travels at a speed of 300 000 000m/s.

taking the distance from the sun to the pluto to be 5.91 X 10^9 km, find the number of seconds that light takes to travel this distance.

The next question is...

7y^2/3 DIVIDE 14y^ -1/2

My answer's 1/2 y^7/6. But the answer on the book comes out as 1/2 y^ 5/6.

dbowie SG

19.7 second for the first one ? I might be wrong as I am using the computer's calculator.
5.91 x 10^9 / Speed of Light = Time in seconds
Thus ,
5.91 x 10^9 / 3 x 10^8 = 19.7

For the second question I got .5y^7/6 too.

bonkysleuth SG

Thanks. But dont you have to convert the unit to either km or metres first before being able to find the time in secs?

wishboy SG

5.91*10^9 km = 5 910 000 000 000 m
Distance = Speed*Time
Time = Distance/Speed
. = 5 910 000 000 000/300 000 000
. = 19700 s

[7y^(2/3)] / [14y^(-1/2)]
= [y^(4/6)] / [2y^(-3/6)]
= (1/2)[y^(4/6 + 3/6)]
= (1/2)y^(7/6)

either ur book answer wrong or u copy the qn wrongly