3x^2+7x+4
Use the FOIL method, 3x•x +3x•1+4•x+4•1
3x^2+7x+4
Answer:
max{x²-4x²+5} = 5 at x = 0
Step-by-step explanation:
1. Find the critical numbers by finding the first derivative of f(x), set it to 0 and solve for x.
We get:
So the critical number is x = 0.
2. Evaluate the first derivative by plugging in the critical number and see if the derivative is positive or negative on both sides:
is positive when the x < 0 (for example: -6*(-1)=+)
is negative when the x > 0 (for example: -6*(1)=-)
Therefore, you have a local maximum.
Now just get the Y value by plugging in the critical number in the original function. 
local maximum is (0,5)
Short side length = x
Medium side = x + 7
Long side = 5x
Total 49, so
x + x + 7 + 5x = 49
If you combine like terms:
7x + 7 = 49
Subtract 7 from both sides
7x = 42
Divide both sides by 7
x = 6 inches
<h3>Answer:</h3>
B) 10 pounds
<h3>Explanation:</h3>
Let x represent the amount of 70¢ candy to be added. The value of the mixture can be written as ...
... 90×30 + 70x = 85×(30+x) . . . . . where 30+x is the total weight of the mix
... 2700 +70x = 2550 +85x
... 150 = 15x . . . . . . add -70x-2550
... 10 = x . . . . . . . . . divide by the coefficient of x
10 pounds of candy at 70¢/lb must be added.
