Think of the 13-ft length of the ladder as the hypotenuse of a right triangle. Represent the horiz. distance from foot of ladder to base of tree by x, or 5 ft.
Represent the vert. dist. from base of tree to top of ladder by y, which is unknown.
Then (13 ft)^2 = (5 ft)^2 + y^2, or
169 ft^2 = 25 ft^2 + y^2. This simplifies to y^2 = 144. Thus y = + 12 feeet.
Note: Please pay attention to your spelling: "lader i up agenst a tree" should be "the top of a 13-ft ladder is placed against a tree."
If it doubles every 4 hours, in 12 hours you will have 3 doublings.
2 * 2 * 2 = 8
90*8 = 720 pounds of algae
Any linear equation can be written as
y = mx+b
where m is the slope and b is the y intercept
m = 1/2 in this case. It represents the idea that the snow fell at a rate of 1/2 inch per hour. In other words, the snow level went up 1/2 an inch each time an hour passed by.
b = 8 is the y intercept. It's the starting amount of snow. We start off with 8 inches of snow already.
The info "snow fell for 9 hours" doesn't appear to be relevant here.
The zeroes are also the x-intercept or the roots of the function
