00:01
In part a, we're going to find the ideal weight of a male who's six feet tall.
00:13
Six feet is six times 12 is 72 inches.
00:19
Our weight function uses inches.
00:22
W at 72 is equal to 50 plus 2 .3 times height is 72 minus 60.
00:33
And that is equal to 77 .6 kilograms.
00:45
In part b, we want to express height as a function of weight.
00:52
We know that weight is 50 plus 2 .3 height minus 60, which is 50 plus 2 .3h.
01:05
Minus 130, then weight minus 50 plus 130 is equal to 2 .3 times the height, or weight plus 80, divided by 2 .3 is equal to h.
01:25
So height is a function of w is w plus 80 over 2 .3.
01:32
Then in part c, we want to verify that, these two functions are each other's inverse and we do that by looking at h of w at h which is the age function was w of h of age plus 80 divided by 2 .3 and then w of h was 50 plus 2 .3 and then w of h was 50 plus 2 .3 times h minus 60.
02:11
So we just substitute that in, and then we add our 80, divide by 2 .3, and that is equivalent to 50 plus 2 .3h minus 130 plus 80 over 2 .3 ,000 ,000, little 50 plus 80, minus 130, cancels out.
02:35
So we have 2 .3h divided by 2 .3 ,000.
02:38
2 .3, which is h...