Okay, so what you need to figure out is that how many years in between 21 1/4 and 37 there are based on the amount the tree grows a year. So, 1 3/4 times 9 is 15.75, and this added to 21 1/4 is 37. This means that it will take the tree 9 years to grow from 21 1/4 ft to 37 ft.
X^2 - x - 20
(x + 4)(x - 5) <==
x^2 - x - 20.....the last sign, which is negative, tells me that one set is positive and one set is negative. The first sign, which is also negative, tells me that the larger number will be negative. Now u have to find 2 numbers, that when added equal -1 and when multiplied, equal -20....those numbers are -5 and 4. so ur answer is : (x + 4)(x - 5)
