I am going to explain this using the substitution method, considering it appears to be the best in this situation.
We know (from the bottom equation) that y can equal 3x+20. Using this knowledge, we substitute the y in the top equation for 3x+20. Now, we have an equation that looks like this:
3x+20=x^2+2x
Now we need to move x to one side and then do some radicals (square roots).
Subtract the 2x on the right (since it is smaller, negatives = NONONO), which will give you
x+20=x^2
Now, we take the square root of both sides to get
rad(x+20)=x
Now we have to simplify. 20 doesn't have a square root, but 4 goes into 20, and 4 has a square root of 2. This now becomes
2rad(x+5)
This doesn't simplify any further... we have a problem... no way to isolate x as far as my knowledge goes... Sorry, can't help you any further than that, but another person or your teacher might be able to. R.I.P...
Answer:

Step-by-step explanation:
D
Due to the question being the question
Answer:
A -60i - 14j
Step-by-step explanation:
u = -9i + 8j
v = 7i + 5j
2u = 2(-9i + 8j) = -18i + 16j
6v = 6(7i + 5j) = 42i + 30j
2u - 6v
(-18i + 16j) - (42i + 30j)
(-18i - 42i) + (16j-30j)
-60i - 14j
Answer:
Step-by-step explanation:
From the given information:
a) To express the weekly profit as a function of price
Cost =C(q) = 1500 + 10q
Revenue = p×q = (50 − 0.1q)×q = 50q - 0.1q²
Revenue = 50q - 0.1q²
Weekly profit = Revenue - Cost
P(q) = (50q -0.1q²) - (1500 + 10q)
P(q)= -0.1 q² + 40 q - 1500
However, q = 500 - 10 p using p = 50 − 0.1q
P= -0.1 (500 - 10 p)² + 40 (500 - 10 p) - 1500
P= -10 p² + 600 p - 6500
b)
The price at which the bottle of the wine must be sold to realise a maximum profit can be determined by finding the derivative and then set it to 0
P' = 0
= -20p+600 = 0
20p = 600
p = 600/20
p = $30
c)
The maximum profit that can be made by the producer is:
P= -10(30)² + 600(30) - 6500
P = - 9000 + 18000 - 6500
P = $2500