For the third line, the guy said when x = 1 the value is 0 (for the third line) HOW IS THAT TRUE

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This goes back to squaring negative numbers. There's two ways to do it, and they can result in different answers.One way is with no parentheses, such as -2^1, -2^2, and -2^3. These would all come out to be -2, -4, and -8 because the negative is not squared with the number. In another perspective, -2^2 is the same as (-1)(2)^2 or (-1)(2)(2) if you expand it.The other way is with parentheses, such as (-2)^1, (-2)^2, and (-2)^3. The answers would be -2, 4, and -8 because here you are actually squaring a negative number. Expanded, it would look like (-2), (-2)(-2), and (-2)(-2)(-2). With (-2)^2, it would result in a positive number since two negative numbers multiplied together result in a positive number.So, going back to -x^2 +1, if x = 1, then the problem would be -1^2 + 1. No parenthesis means -1 is multiplied to the number, so we get -1 + 1, and the value is 0.~ Azaler