F(x) = -x^2 + 3x + 8
f'(x) = -2x + 3
when f(x) is increasing f'(x) > 0
-2x + 3 > 0
-2x > -3
x < 3/2 or 1.5
So the required interval is (-infinity,1.5).The first choice.
Answer:
a) A shopkeeper marked the price of an article a certain percentage above the cost price and he allowed 16% discount to make 5% profit. If a customer paid Rs 9.492 with 13% VAT to buy the article, by what percent is the marked price above the cost of the price article? (I hope this helps)
Answer:
The rate of change in distance between the spy and the rocket is 10.8 km/min,
or about 180 m/sec.
Step-by-step explanation:
At "Time=0" the rocket is 6km from the spy.
The rocket travels vertically 8km in about 0.37 minutes, calculated by 8km÷21.6km/min.
At that point, the rocket is 10 km from the spy., calculated by 6²+8²=10²
The difference is 4 kiilometers over 0.37minutes, about 22.2 seconds
Divide Distance by Time to get Rate:
4km/0.37min = 10.8 km/min
That is about 180 meters per second.
Answer:
Perpendicular.
Step-by-step explanation:
Find the slopes of each line through 
Line a:
m = (-10-4) / (8--4)
= -14/12
= -7/6
Line b:
m = (20-8) / (18 -4)
= 12/14
= 6/7
When lines are parallel, they have the same slope. Since -7/2≠6/7, they are not parallel.
When lines are perpendicular, the product of the slopes equals -1.
-7/6 x 6/7 = -1
The product is -1, hence they are perpendicular lines.
