Answer:
a) 70
b) 10π ft²/ft
c) 0.24 ft/sec
Step-by-step explanation:
1) y = x³ + 2x

or
= 
at
and x = 2
= 
or
= 60 + 10 = 70
2) A = πr² ft²

or
= 2(πr)
at r = 5 ft
= 2(π × 5) ft²/ft
or
= 10π ft²/ft
3) From Pythagoras theorem
Base² + Perpendicular² = Hypotenuse²
Thus,
B² + P² = H² .............(1)
here, H = length of the ladder
P is the height of the wall
B is the distance from the wall at bottom
or
B² + P² = 25² ...........(1)
at B = 20 ft
20² + P² = 25²
or
P² = 625 - 400
or
P = √225
or
P = 15 ft
differentiating (1) with respect to time, we get

at B = 20 ft,
and P = 15 ft
⇒ 2(20)(0.18) +
= 0
or
= - 7.2
or
= - 0.24 ft/sec (Here negative sign depicts the ladder slides down)
Answer:
C
Step-by-step explanation:
Answer:
Step-by-step explanation:
The original selling price of the pair of socks is $8. The pair of socks is on sale for 15%. The new selling price of the pair of socks would be the original price - 15% off the original price. It becomes
8 - (15/100 × 8) = 8 - 0.15×8 = 8 - 1.2 = $6.8
if the sales tax rate is 8%, it means that the total cost of the socks would be the new selling price + 8% of the new selling price. It becomes
Total cost of the pair of socks
= 6.8 + (8/100×6.8) = 6.8 + 0.08×6.8 = 6.8 + 0.544 = $7.344