I'll just factor the above equation.
x² + 18x + 80
x² ⇒ x * x
80
can be:
1 x 80
2 x 40
4 x 20
5 x 16
8 x 10 Correct pair
(x+8)(x+10)
x(x+10) +8(x+10) ⇒ x² + 10x + 8x + 80 = x² + 18x + 80
x+8 = 0
x = -8
x+10 = 0
x = -10
x = -8
(-8)² + 18(-8) + 80 = 0
64 - 144 + 80 = 0
144 - 144 = 0
0 = 0
(-10)² + 18(-10) + 80 = 0
100 - 180 + 80 = 0
180 - 180 = 0
0 = 0
I think the algebra tiles will not be a good tool to use to factor the quadratic equation because the equation is not a perfect square quadratic equation.
Answer:
Interest rate ≈ 3.48%
Step-by-step explanation:
Formula
====
d = r * t
Givens
======
d = 2 3/4
t = 1 hour 15 minutes
r = ????
Calculations
==========
You need to convert the 15 minutes to hours.
1 hour = 60 minutes
x hour = 15 minutes
1/60 = x/15
x = 15/60
x = 0.25 hours
so the time = 1 hours + 0.25 hours
t = 1.25 hours
Now you need to do something with the distance.
3/4 mile = 0.75 of a mile
So the distance = 2 + 0.75 = 2.75 miles
Now you are ready for the answer.
d = r * t you are looking for r
2.75 = r * 1.25
r = 2.75/1.25
r = 2.2 miles / hour
Note you could do this with fractions.
2 3/4 = 11/4
1 1/4 = 5/4
r = 11/4 // 5/4 =11/5 = 2 1/5 which is the same thing as 2.2. If your calculator can handle fractions (those kind of calculators cost about 10 dollars in Canada. It should be 8 in the US) that might be the way to do this problem.
For this case we have that by definition, the equation of a line of the slope-intersection form is given by:
Where:
m: It's the slope
b: It is the cut-off point with the y axis
We have two points through which the line passes, so we can find the slope:
Thus, the equation is of the form:
We substitute one of the points and find "b":
Finally, the equation is of the form:
ANswer:
