Rearrange to: x^2 + 18x - 25 = 0
Then factorise (I like to do it by completing the square):
(x + 9)^2 -81 -25 = 0
(x + 9)^2 = 106
x + 9 = sqrt(106)
The sol'ns are:
x = -9 + and - sqrt(106)
8000-4.989 so when you see the word less than it means that you have to subtract and more than you have to add so the answer for this question will be 7,995.011
10 will be your answer because 4 x 5 divided by 2 is 10
Circunference=diameter time pi
aprox pi to 3.14
circunference=200.332
subsitue
200.332=diameter time s3.14
divide both sides by 3.14
63.8=diameter
answer is 63.8 units
