Formulae and simultaneous equations (Chapter 7) 1675 Let A=b
b+c. Find the value ofcwhen:
a A=2, b=6 b A=3, b=¡ 9 c A=¡ 1 , b=5
6 Solve simultaneously, by substitution:
a y¡ 5 x=8 and y=3x+6 b 3 x+2y=4 and 2 x¡y=5.
7 Solve simultaneously: y=4x¡ 1 and 3 x¡ 2 y=¡ 8.
8 Solve simultaneously:
a 2 x+3y=5
3 x¡y=¡ 9b 4 x¡ 3 y¡2=0
5 x¡ 2 y=139 3 sausages and 4 chops cost$12: 40 , and 5 sausages and 3 chops cost$11: 50. Find the cost of each
item.
10 Drivers are fined$ 200 for exceeding the speed limit by up to 15 km/h, and$ 450 for exceeding
the speed limit by more than 15 km/h. In one night, a policeman gave out 22 speeding fines worth
a total of$ 6650 :How many drivers were caught exceeding the speed limit by more than 15 km/h?Review set 7B #endboxedheading
1 The strengthSof a wooden beam is given by S= 200w^2 t units,
wherewcm is its width andtcm is its thickness.
Find:
a the strength of a beam of width 16 cm and thickness 4 cm
b the width of a 5 cm thick beam of strength60 000units.2aMakeythe subject of 6 x+5y=20.
b Makerthe subject of C=2¼r.3 The surface area of a sphere is given by the formula A=4¼r^2. If the surface area of a sphere
is 250 cm^2 , find its radius correct to 2 decimal places.4 Makexthe subject of: a K=6
y¡ 2 xb M=5 c
p
2 x
5 Write a formula for the total cost$Cof packing parcels of books for dispatch if the charge is:
a $ 2 per parcel plus$ 1 : 20 for one book
b $ 2 per parcel plus$ 1 : 20 per book for 5 books
c $pper parcel plus$ 1 : 20 per book forbbooks
d $pper parcel plus$xper book forbbooks.6 Solve simultaneously:
a y=3x+4 and y=¡ 2 x¡ 6 b y=3x¡ 4 and 2 x¡y=8.
7 Solve simultaneously: 2 x¡ 5 y=¡ 9 and y=3x¡ 3
8 Solve the following using the method of elimination: 3 x¡ 2 y=3and 4 x+3y=4.
9 The larger of two numbers is 2 more than three times the smaller number. If their difference is 12 ,
find the numbers.twIGCSE01
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Y:\HAESE\IGCSE01\IG01_07\167IGCSE01_07.CDR Monday, 15 September 2008 4:57:38 PM PETER