All of these involve simple substitution. Just replace the variable with the actual value.
8z + 3 >>> 8(8) + 3 = 64 + 3 = 67
3(7+ x^2) >>> 3(7 + 2^2) = 3(7 + 4) = 3(11)=33
s - 5t + s^2 >>> 4 - 5(-1) + 4^2 = 4 + 5 + 16
Get the trend? I am not sure I get that last one, is it:
x - y*3^2?
Answer:
B,D
Step-by-step explanation:
Just use PEMDAS, comment in more explanation is needed
To solve for the time it takes to travel a certain distance at a certain speed, use the formula,
time = distance / speed
Given that the entire journey takes four hours, add up the time it takes David to row upstream with that of him travelling downstream. This is mathematically represented as,
total time = time upstream + time downstream
4 = 3/(x - 1) + 3/(x +1)
Solving for x in the equation gives 2. Thus, David's speed in still water is 2 miles per hour.
(4,1) is the midpoint. Just find the middle of the two numbers and that will be your new point. Hope this helps!
