00:01
Okay, so part a wants us to find the truth value of for all x and for all y, and i've had his real numbers.
00:07
X squared equals y squared implies x equals y.
00:11
This is false.
00:13
Negative four.
00:16
Sorry, i might have i said it one more time.
00:21
So 16, which is 4 squared, equals negative 4 quantity squared, which is 16.
00:29
So this is true, but negative 4 does not equal 4.
00:33
So that's a counter example.
00:35
Part b, for all x, there exists a y, such that x equals y squared.
00:42
That's not true because if x is negative, so x is like negative 1, there is no y that gives you something positive squared.
00:50
So because y square, y squared is always positive...