F.2maths 10marks!!

1. c=5/9(F-32)
9c/5=F-32
9c/5+32=F
F =9c/5+32
2. 2x-3y=7---1)
4x+5y=3---2)
1)x2-2)
2(2x-3y)-(4x+5y)=2(7)-3
4x-6y-4x-5y=11
-11y=11
y = - 1 ---3)
3)into 1)
2x-3y=7
2x-3(-1)=7
2x+3=7
2x=4
x=2
3.

Since these equations represent two lines in thexy-plane, the simultaneous solution of these two equations (i.e. those points(x,y) that satisfy both equations) is merely the intersection of the two lines.

The three possible cases should be:
non-parallel lines( one solution)
圖片參考：http://www.math.oregonstate.edu/home/programs/undergrad/CalculusQuestStudyGuides/vcalc/system/system2.gif
and identical

lines(infinite solutions).
圖片參考：http://www.math.oregonstate.edu/home/programs/undergrad/CalculusQuestStudyGuides/vcalc/system/system3.gif

4. 36km/h=x m/s, what is x?
36000/3600 = 10 (m)
5. Simplify the ratios.
(a) 40cm:25km
= 40:2500000
=4:250000
=1:62500
(b)1.7kg:680mg
=1700000:680
=170000:68
=2500:1
(c)1m^2:1cm^2
= 10000:1
(d)1km/h:1m/s
=1000:3600
=10:36
=5:18