00:01
So we have the following problems or parts to problem one, and we need to show that the contrapositive, we need to find the contrapositive of each statement and prove or just prove it.
00:13
So either say it's true or false.
00:17
So let's start with this first part.
00:19
So 3x minus 7 not equal to 11 implies x is not equal to 7.
00:24
To do the contrapositive, we start with the second term and negate it.
00:28
So not equal is just equal.
00:32
And we do the same thing for the first part here.
00:36
So this would be 3x minus 7 is equal to 11.
00:40
So is this statement true? well, 3 times 7 minus 7.
00:46
That's 21 minus 7.
00:49
And that is equal to 14.
00:53
So that's not equal to 11.
00:56
So i'm going to put down f for false.
01:00
So up here, t for true and f for false.
01:08
Now let's go to b.
01:09
It's the contrapositive here, similar to part a.
01:14
5x plus 7 equals 22 implies x is equal to 3.
01:20
Let's go ahead and just solve for x in this first equation.
01:24
So we can subtract both sides by 7 and i'll, i have enough room here.
01:33
5x is equal to 22 minus 7 is 15.
01:38
So x, if we divide both sides by 5, x is indeed 3.
01:44
So that is a true statement.
01:50
Now for part c, if a is not equal to 3, then the absolute value of a is not equal to 3.
01:57
So the contrapositive, we start with this part.
02:00
So not equal is equal.
02:03
And then that's a is equal to 3.
02:06
And this is false because the absolute value of negative 3 is equal to 3, but negative 3 is not equal to 3.
02:21
They have different signs.
02:24
Let's go on to d...