00:01
The thought process on this problem is just that you are plugging in for the x's, so x squared plus 7x.
00:09
And when the first thing is saying evaluate f of zero, sometimes what i'll actually do is just have students write out the things without x's and then replace the xes with zero.
00:24
So you're looking at zero squared zero times zero is zero, seven times zero is zero, and zero plus zero is zero.
00:30
So then moving on to the next one where we're doing f of 3, same thing.
00:38
But it's 3 squared plus 7 times 3.
00:42
So we're looking at 3 squared, 3 times 3 is 9, 7 times 3 is 21.
00:47
So you get 30 when you add those together.
00:52
But then that's very different than doing f of negative 3.
00:56
Because think about how when you square something, that means multiply by itself.
01:00
And then we also have 7 times negative 3...