# function simple ....but the answer not logic for me

• Mar 27th 2008, 10:39 AM
nikk
function simple ....but the answer not logic for me
1. Given set A = {9, 36, 49, 64} and set B = {-8, -6, 3, 4, 6, 7, 8}. The relation from set A
to set B is "the square root of ", state

(a) the range of the relation,

(b) the object of 8,

(c) the image of 49.
[ 3 marks ]

ans given:

a) {3,6,7,8} ---- my ans { 8,7,6,3,-6,-8}
b) 56 ---- my ans 64
c) 7 ---- my ans 7 (logic)

hope i can get help

below is my arrow diagrame:
http://img155.imageshack.us/my.php?i...mathvi4.th.png

and the calculation of mapping as below

calculation "the square root of "

(a) the square root of 9 is +3 or -3 (-3 ignore)

(b) the square root of 36 is +6 or -6

(c) the square root of 49 is 7 or -7 (-7 ignore)

(c) the square root of 64 is +8 or -8
• Mar 27th 2008, 11:09 AM
Plato
Quote:

Originally Posted by nikk
1. Given set A = {9, 36, 49, 64} and set B = {-8, -6, 3, 4, 6, 7, 8}. The relation from set A
to set B is "the square root of ", state
(a) the range of the relation,
(b) the object of 8,
(c) the image of 49.
ans given:
a) {3,6,7,8} ---- my ans { 8,7,6,3,-6,-8}
b) 56 ---- my ans 64
c) 7 ---- my ans 7 (logic)

I agree with the given answers for parts a) & c).
There may be others who disagree with my using the convention that "the square root of " refers to a single non-negative number. But your text seems to be using that convention.

I do not know what your text means by ‘object’.
If it is what is usually called ‘pre-image’ then I agree with your answer 64.
• Mar 27th 2008, 11:26 AM
nikk
Quote:

Originally Posted by Plato
I agree with the given answers for parts a) & c).
There may be others who disagree with my using the convention that "the square root of " refers to a single non-negative number. But your text seems to be using that convention.

I do not know what your text means by ‘object’.
If it is what is usually called ‘pre-image’ then I agree with your answer 64.

tq mr ploto for your help & opinion ...(Yes)(Handshake)

it mean you consider +ve ans not the -ve ans????

but i still have some new confusing here..is it this statement is correct or not

the relation from set A to set B is "the square root of "

is it logic
(a) 9 is "the square root of " 3
(b)36 is "the square root of " + 6 or -6
and etc..... base on the mapping of set A to Set B??

so for me may be the question should be
set A = {-8, -6, 3, 4, 6, 7, 8}
set B = {9, 36, 49, 64}

instate of the original question
• Mar 27th 2008, 11:36 AM
Plato
Is English a second language for you? If so this confusion is completely understandable.
5 is the square root of 25.
25 is the square of both 5 and –5.
But again,
the convention is: "the square root of a number " refers to a single non-negative number whose square is the number.
• Mar 27th 2008, 06:13 PM
nikk
Quote:

Originally Posted by Plato
Is English a second language for you? If so this confusion is completely understandable.
5 is the square root of 25.
25 is the square of both 5 and –5.
But again,
the convention is: "the square root of a number " refers to a single non-negative number whose square is the number.

hai mr ploto tq very much for helping me....now i understand