chetan2u wrote:
Bunuel wrote:
If x and y are integers each with absolute value less than 5 and 7x - 6y = 3, how many values of x are there?
A. 1
B. 2
C. 3
D. 4
E. 5
Hi,
A way to do such Qs..
7x-6y=3...
7x=6y+3=3(2y+1)....
We can see from this that x HAS to be a multiple of 3..
Possible values are 3&-3..
But remember to check:-
if these values have y as an integer..
2y+1 can take any ODD values
And for X=3, y=3..
X=-3, y is -4..
So both are OK...
B
Hi
chetan2u, nice explanation, thank you.
Can you explain this part again if you don't mind?
Quote:
But remember to check:-
if these values have y as an integer..
2y+1 can take any ODD values
And for X=3, y=3..
X=-3, y is -4..
So both are OK...
and this
Quote:
We can see from this that x HAS to be a multiple of 3..
Possible values are 3&-3..
I've a sort of weakness with this type of questions :/ Any theory you can suggest in this regard?
If we have co-prime numbers and x and y are integers then those variables x and y will be multiple of those PRIME numbers..
Similarly here when you say 7x=3(2y+1)....
In 7x, there has to be a multiple of 3 as RHS is a multiple of 3... So x is a multiple of 3