step 1
Find out the slope WX
W(2,-3) and X(-4,9)
m=(9+3)/(-4-2)
m=12/-6
m=-2
step 2
Find out the slope YZ
Y(5,y) and Z(-1,1)
m=(1-y)/(-1-5)
m=(1-y)/-6
m=(y-1)/6
step 3
Remember that
If two lines are perpendicular
then
their slopes are negative reciprocal
that means
(y-1)/6=1/2 -----> because the negative reciprocal of -2 is 1/2
solve for y
2y-2=6
2y=6+2
2y=8
<h2>y=4</h2>
How many 6-digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, if repetitions of digits are allowed?
sveta [45]
There are 6 digits. Each digit can take ten different numbers except for the first digit since it cannot be zero.
So:
9 x 10 x 10 x 10 x 10 x 10
900000 numbers.
Another way of thinking about this is to just count up to 999,999. Obviously there are 999,999 different numbers here. But since our number has to have 6 digits in them, we have to delete 99,999 numbers. Thus there are 900,000 different numbers.
