If $x + y = 10$ and $x^2 - y^2 = 40$, what is the value of $2x + 3y$?
x is larger than y.
thus xy pairs are
6,4
7,3
8,2
9,1
10,0
So
36 - 16 = 20
49 - 9 = 40.
x = 7, y=3
You can take it from here.
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Also fix your latex in the future.
There's a latex buttonnext to "image"
Can also do this as follows:
x + y = 10 (1)
x2 - y2 = 40 This can be written as (x+y)(x-y) = 40. Use (1) to get 10*(x - y) = 40 or
x - y = 4 (2)
Add (1) and (2): 2x = 14, so x = 7
Put this in (1) to get 7 + y = 10 or y = 3