Page 46 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

= 1

x - y = = 1
iii a - b = (a + b) (a - b)
2
2
x - y = (x + y) (x - y)
2
2
= 9 x 1
x - y = 9
2
2
iv a + b = (a + b) (a + b - ab)
2
3
3
2
x + y = (x + y) (x2 + y2 - xy)
3
3
= 9 (41 - 20)
= 9 x 21
x + y = 189
3
3
v a - b = (a - b) (a + b + ab)
3
3
2
2
x - y = (x - y) (x2 + y2 + xy)
3
3
= 1 (41 + 20)
= 1 x 61
= 61
x - y = 61
3
3
vi x + y = 9
x - y = 1
----------------------
2x = 10
----------------------

x = = 5
If x = 5, 5 + y = 9
y = 9 - 5 = 4
x = 5; y = 4

2 Solve (x + 5) - (x - 5) 2
2
If x + 5 = a and x - 5 = b
a - b = (a + b) (a - b)
2
2
(x + 5) - (x - 5) = [(x + 5) + (x - 5)] [(x + 5) - (x - 5)]
2
2
= (x + 5 + x - 5) (x + 5 - x + 5)
= (2x) (10)
= 20 x
3 If (x - y) = 4 and xy = 12, find the value of (x2 + y2)
(x - y) = x + y - 2xy
2
2
2
(4) = x + y - 2 x 12
2
2
2
16 = x + y - 24
2
2
x + y - 24 = 16
2
2
33

CITS : WCS - Electrical - Exercise 4