Answer:
1. B 2. C
Step-by-step explanation:
1. x^2-18x+(18/2)^2=19+(18/2)^2
(x-18/2)^2=100
(x-9)^2=100
x1= -1 x2= 19
2. x^2=81
x=+-9
x1=-9 x2=9
Pythagoras' theorem:
b^2 = c^2 - a^2
Substitute in the values:
b^2 = 13^2 - 12^2
b^2 = 25
Square root it
b = 5km
The answer is option B. 5km
Answer:
140 minutes
Step-by-step explanation:
After 28 mins you've gone 4 miles, assuming this rate is constant and you dont slow down or speed up, in order to get to 20 miles you will have run 5x as much (20/4 = 5), thus 5x the amount of time (28x5).
20/4 = 5
5x28 = 140