Solve for x 3 (x- 4) = 44 - 5x A: 4 B: 5 C: 6 D: 7

A fence is to be built to enclose a rectangular area of 1800 square feet. The fence along three sides is to be made of material

drek231 [11]

Answer:

length = 60 foot, width = 30 foot

Step-by-step explanation:

Area of rectangular part, A = 1800 ft²

Cost of fencing three sides is $ 6 per foot and cost of one side fencing is $18 per foot.

Let the length of the rectangle is l and the width of the rectangle is W.

Area = Length x width

A = L x W

1800 = L x W ...... (1)

Total cost of fencing, C = 6 x ( L + W + L) + 18 x W

C = 6 (2L + W) + 18 W

C = 12 L + 24 W

Substitute the value of W from equation (1), $W=\frac{1800}{L}$ in equation (2)

$C=12L+24\times \frac{1800}{L}$

$C=12L+\frac{43200}{L}$

Differentiate both sides with respect to L:

$\frac{dC}{dL}=12-\frac{43200}{L^{2}}$

Put it equal to zero for maxima and minima

$12-\frac{43200}{L^{2}}=0$

L = 60 foot

and W = 30 foot

So, the costing is minimum for length = 60 foot and the width = 30 foot.

4 0

3 years ago

PLSSS HELPPP find the surface area of the regular pyramid ILL GIVE BRAINLIEST

lina2011 [118]

Answer:

i know the answer to four just not 3 so you don’t have to mark me brainliest it’s 108.8153

Step-by-step explanation:

5 0

2 years ago

Write the equation of a line that has a slope of 3 and goes through points (2,1)

Inga [223]

Answer:

The equation of straight line is 3 x-y-5=0

Step-by-step explanation:

The equation of straight line having slope m = 3 and passing through the point (2,1) is

the standard form of straight line is $y-y_{1} = m (x-x_{1} )$

now substitute m = 3 and point (2,1) is

$y- 1 = 3(x-2)$

$y - 1 = 3 x - 6$

$3 x-y -6+1=0$

$3 x-y -5 =0$

The equation of straight line is 3 x-y-5=0

3 0

3 years ago

If a bacteria population starts with 80 bacteria and doubles every three hours, then the number of bacteria after t hours is n =

Thepotemich [5.8K]

Answer:

$f^{-1}(x)=3\frac{ln(\frac{t}{80})}{ln(2)}$

It will take 20.9 hours to reach 10000

Step-by-step explanation:

$f(t)=80(2)^{\frac{t}{3}}$

To find inverse of the function , replace f(x) with y

$y=80(2)^{\frac{t}{3}}$

swap the variables

$t=80(2)^{\frac{y}{3}}$

solve the equation for y

$t=80(2)^{\frac{y}{3}}\\\\\frac{t}{80} =(2)^{\frac{y}{3}}$

take ln on both sides

$ln(\frac{t}{80} )= \frac{y}{3} ln(2)\\\\\frac{ln(\frac{t}{80} }{ln(2)} =\frac{y}{3}\\3\frac{ln(\frac{t}{80} }{ln(2)} =y$

the inverse function is

$f^{-1}(x)=3\frac{ln(\frac{t}{80})}{ln(2)}$

for part b plug in 10000 for t in f^-1(x)

$f^{-1}(10000)=3\frac{ln(\frac{t}{80} }{ln(2)} \\f^{-1}(10000)=3\frac{ln(\frac{10000}{80} }{ln(2)} \\=20.89$

It will take 20.9 hours to reach 10000

7 0

4 years ago

If g (x)= x^2-5, where does the graph g (x) cross the x-axis?

Vlad [161]

The graph crosses the x axis where g(x) = 0 , so:-

x^2 - 5 = 0
x^2 = 5
x = sqrt5 or -sqrt5

so grapg corosses the x axis at (-sqrt5,0) and (sqrt5, 0)

3 0

3 years ago