1400 is you're answer because 25x14=350×4=1,400
Hello!
To solve this problem, we will use a system of equations. We will have one number be x and the other y. We will use substitutions to solve for each variable.
x+y=9
x=2y-9
To solve for the two numbers, we need to solve the top equation. The second equation shows that x=2y-9. In the first equation, we can replace 2y-9 for x and solve.
2y-9+y=9
3y-9=9
3y=18
y=6
We now know the value of y. Now we need to find x. We can plug in 6 for y in the second equation to find x.
x=2·6-9
x=12-9
x=3
Just to check, we will plug these two numbers into the first equation.
3+6=9
9=9
Our two numbers are three and six.
I hope this helps!
Answer:
- front/back: 106 2/3 ft
- sides: 135 ft
Step-by-step explanation:
These problems are easily solved if you start with the knowledge that the solution makes the front/back cost equal to the side cost.
Suppose we define the length of the front as x. Then the total cost of the front and back is (2x)(81) = 162x.
If y is the length of the side of the building, then (2y)(64) = 128y is the total cost of the sides of the building. When these costs are equal, we have ...
162x = 128y
y = (162/128)x
The floor area is ...
xy = 14400 = x(162/128)x
x = √(14400·128/162) = √(11377 7/9) = 106 2/3
y = (162/128)x = 135
The front/back of the building measure 106 ft 8 inches; the sides measure 135 feet.
_____
<em>Solution using derivatives</em>
Using the above variable definitions, we can find the side length as ...
y = 14400/x
so the total cost is then ...
c = 162x + 128(14400/x)
We want the derivative with respect to x to be zero:
dc/dx = 0 = 162 -128·14400/x^2
Solving for x gives ...
x = √(14400·128/162) = 106 2/3 . . . . . compare to the solution above
y = 14400/(106 2/3) = 135
Answer:
-4
Step-by-step explanation:
f(x) = 10 - 2x
substitute 7 in place of x
f(7) = 10 -2*7
=10 - 14
=-4
therefore the value of f(7) is -4.
Answer:
Step-by-step explanation:
Slope intercept form is where <em>m </em>is the slope and <em>b </em>is the y-intercept.
Slope is or in this case =
Substitute one of the coordinates for x and y. I am going to use (0, -4) so:
since m = 2 and b = -4, we can conclude that the equation would be