goodyear2013 wrote:
For integers, \(x\) and \(y, x=y+2.\) From the table below, select the values that could correspond to \(x\) and \(x^2 − y^2.\)
Given : x=y+2 ----> y = x-2
To find : x & (x^2 - y^2).
How can you solve it it in a faster way ?
Bring it in terms of X. Why ? Because , we have to find the value of
x and we are given answer choices for value of
x.
So,
(x^2 - y^2) = [x^2] - [(x-2)^2] = [x^2] - [x^2 + 4 - 4x] = x^2 - x^2 - 4 + 4x = 4x -4
Therefore, (x^2 - y^2) = 4x-4
Now as soon as you put , x=21 , 4x-4 = (21*4) - 4 = 80.
Hence ,
21 and
80 are the answers respectively for
x &
(x^2 - y^2).
Hope it helps.