[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.88,0:00:13.00,Default,,0000,0000,0000,,We're asked to evaluate the expression a squared plus ten b minus eight when a is equal to seven and b is equal to negative four.
Dialogue: 0,0:00:13.00,0:00:19.27,Default,,0000,0000,0000,,So to evaluate the expression we really just need to substitute a with 7 and substitute b with negative 4.
Dialogue: 0,0:00:19.27,0:00:24.13,Default,,0000,0000,0000,,Because they are saying evaluate it when a is seven and b is negative four. So let's do that.
Dialogue: 0,0:00:24.13,0:00:29.40,Default,,0000,0000,0000,,So everywhere we see an a in the expression we should put a seven there. So instead of a squared
Dialogue: 0,0:00:29.40,0:00:42.27,Default,,0000,0000,0000,,we should write seven squared plus ten times b. But instead of a b there we are
Dialogue: 0,0:00:42.27,0:00:50.40,Default,,0000,0000,0000,,now going to substitute it with b is equal to negative four. So ten times negative four instead of the
Dialogue: 0,0:00:50.40,0:00:58.53,Default,,0000,0000,0000,,b right over there. And then we have the minus eight. And now we just have to evaluate this thing.
Dialogue: 0,0:00:58.53,0:01:07.47,Default,,0000,0000,0000,,Seven squared is forty-nine. And then ten times negative four, remember order of operations.
Dialogue: 0,0:01:07.47,0:01:12.40,Default,,0000,0000,0000,,Multiplication comes before addition so we have to multiply this. Ten times negative four is
Dialogue: 0,0:01:12.40,0:01:22.00,Default,,0000,0000,0000,,negative forty. So it's plus negative forty, and then we have minus eight over here.
Dialogue: 0,0:01:22.00,0:01:28.93,Default,,0000,0000,0000,,And so we get forty-nine plus negative forty, which is the same thing as forty-nine minus forty, is going
Dialogue: 0,0:01:28.93,0:01:35.00,Default,,0000,0000,0000,,to be nine. Then we're going to subtract eight from that. And so we get one.
Dialogue: 0,0:01:35.00,0:01:40.60,Default,,0000,0000,0000,,Forty-nine minus forty is nine, and minus eight is one. We are done.
Dialogue: 0,0:01:40.60,9:59:59.99,Default,,0000,0000,0000,,We have evaluated the expression when a is equal to seven and b is equal to negative four.