1) Simplify: 2/x-1 - 3/x 2) Some cases have to be lifted by a craneEach case has a mass of 68kg, correct to 2significant figuresa) write down the upper boundb) A crane can lift safely a load of 1200kg, correct to 2 significant figuresFind the greatest number of cases that the crane can lift safely in one load.THANK YOU, (WITH METHOD PLEASE!!!)
1Imagine these are fractions such as 2/5 - 3/6You have to multiply the left number by 6/6 and the right one by 5/5, right? You do something very similar here, so you multiply 2/(x-1) by x/x giving you 2x/(x(x-1))Then you multiply 3/x by (x-1)/(x-1) giving you 3(x-1)/(x(x-1))You now have: 2x/(x(x-1)) - 3(x-1)/(x(x-1)) You can simplify this to: 2x/(x(x-1)) - 3x-3/(x(x-1)) so -x-3/(x(x-1)) You can then simplify the denominator which I'm sure you can do2a) 68.5 kg b) To find the number of cases it can lift you have to use: (the maximum mass it can lift)/(the mass of each case) To get the greatest number you have to have the largest possible number on top and smallest on the bottom (ie 15/2 is larger than 13/4) if 1200 is correct to 2sf it can be between 1150 and 1250 68 can be between 67.5 and 68.5 Therefore, you do 1250/67.5 You have to round your final answer DOWN to 0 decimal places no matter how big the 1st decimal place is because you can't have 0.35 of a case or whatever Good luck with your GCSEs ;)
