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Nana76 [90]
3 years ago
15

-4x + 7 for x=1. evaluate each expression for the given value of x.

Mathematics
2 answers:
Crazy boy [7]3 years ago
6 0
-4(1)+7=-4+7=3
the answer is 3
Zarrin [17]3 years ago
3 0
-4(1)=-4+7=3
answer: 3
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Jim provides photos for two online sites: site A and site B. Site A pays $0.85 for every photo Jim provides. The amount in dolla
yarga [219]
We can use the same equation to figure out with only substituting the amount he was paid per photo.

Site A    y = $0.85x      =  $0.85(5)  =  $4.25
Site B    y = $0.40x      =  $0.40(5)  =  $2.00

We can see that Jim was paid $2.25 more at site A than Site B.
6 0
3 years ago
Read 2 more answers
What is the rule for the reflection?
Sliva [168]
Hey user!

your answer is here...

laws ( rules ) of reflection are :-

• angle of incidence is equal to angle of reflection.

• the incident ray, Normal ray and reflected ray all lie in same plane.

cheers!!

7 0
3 years ago
EXAMPLE 5 Find the maximum value of the function f(x, y, z) = x + 2y + 11z on the curve of intersection of the plane x − y + z =
Taya2010 [7]

Answer:

\displaystyle x= -\frac{10}{\sqrt{269}}\\\\\displaystyle y= \frac{13}{\sqrt{269}}\\\\\displaystyle z = \frac{23\sqrt{269}+269}{269}

<em>Maximum value of f=2.41</em>

Step-by-step explanation:

<u>Lagrange Multipliers</u>

It's a method to optimize (maximize or minimize) functions of more than one variable subject to equality restrictions.

Given a function of three variables f(x,y,z) and a restriction in the form of an equality g(x,y,z)=0, then we are interested in finding the values of x,y,z where both gradients are parallel, i.e.

\bigtriangledown  f=\lambda \bigtriangledown  g

for some scalar \lambda called the Lagrange multiplier.

For more than one restriction, say g(x,y,z)=0 and h(x,y,z)=0, the Lagrange condition is

\bigtriangledown  f=\lambda \bigtriangledown  g+\mu \bigtriangledown  h

The gradient of f is

\bigtriangledown  f=

Considering each variable as independent we have three equations right from the Lagrange condition, plus one for each restriction, to form a 5x5 system of equations in x,y,z,\lambda,\mu.

We have

f(x, y, z) = x + 2y + 11z\\g(x, y, z) = x - y + z -1=0\\h(x, y, z) = x^2 + y^2 -1= 0

Let's compute the partial derivatives

f_x=1\ ,f_y=2\ ,f_z=11\ \\g_x=1\ ,g_y=-1\ ,g_z=1\\h_x=2x\ ,h_y=2y\ ,h_z=0

The Lagrange condition leads to

1=\lambda (1)+\mu (2x)\\2=\lambda (-1)+\mu (2y)\\11=\lambda (1)+\mu (0)

Operating and simplifying

1=\lambda+2x\mu\\2=-\lambda +2y\mu \\\lambda=11

Replacing the value of \lambda in the two first equations, we get

1=11+2x\mu\\2=-11 +2y\mu

From the first equation

\displaystyle 2\mu=\frac{-10}{x}

Replacing into the second

\displaystyle 13=y\frac{-10}{x}

Or, equivalently

13x=-10y

Squaring

169x^2=100y^2

To solve, we use the restriction h

x^2 + y^2 = 1

Multiplying by 100

100x^2 + 100y^2 = 100

Replacing the above condition

100x^2 + 169x^2 = 100

Solving for x

\displaystyle x=\pm \frac{10}{\sqrt{269}}

We compute the values of y by solving

13x=-10y

\displaystyle y=-\frac{13x}{10}

For

\displaystyle x= \frac{10}{\sqrt{269}}

\displaystyle y= -\frac{13}{\sqrt{269}}

And for

\displaystyle x= -\frac{10}{\sqrt{269}}

\displaystyle y= \frac{13}{\sqrt{269}}

Finally, we get z using the other restriction

x - y + z = 1

Or:

z = 1-x+y

The first solution yields to

\displaystyle z = 1-\frac{10}{\sqrt{269}}-\frac{13}{\sqrt{269}}

\displaystyle z = \frac{-23\sqrt{269}+269}{269}

And the second solution gives us

\displaystyle z = 1+\frac{10}{\sqrt{269}}+\frac{13}{\sqrt{269}}

\displaystyle z = \frac{23\sqrt{269}+269}{269}

Complete first solution:

\displaystyle x= \frac{10}{\sqrt{269}}\\\\\displaystyle y= -\frac{13}{\sqrt{269}}\\\\\displaystyle z = \frac{-23\sqrt{269}+269}{269}

Replacing into f, we get

f(x,y,z)=-0.4

Complete second solution:

\displaystyle x= -\frac{10}{\sqrt{269}}\\\\\displaystyle y= \frac{13}{\sqrt{269}}\\\\\displaystyle z = \frac{23\sqrt{269}+269}{269}

Replacing into f, we get

f(x,y,z)=2.4

The second solution maximizes f to 2.4

5 0
3 years ago
You need to cover the playground of a child development center with mulch. the playground is 125 feet long and 60 feet wide. you
kirill [66]
The answer is 139 cubic yards

This mulch will be of cylindrical shape.
The volume (V) of a cylinder is: 
V = l · w · h           (l - length, w - width, h - height (in our example, height = depth)

It is known:
l = 125 feet
w = 60 feet
h = 6 inches = 0.5 feet

V = l · w · h = 125 · 60 · 0.5 = 3750 feet³

Since 1 cubic foot is 0.037 cubic yards, 3750 cubic feet are 139 cubic yards:
0.037 ·  3750 feet³ = 138.75 cubic yards ≈ 139 cubic yards
4 0
3 years ago
There is an 80% chance of rain tomorrow and a 20% chance the football game will be postponed. What is the probability that it wi
OlgaM077 [116]
First turns those into fractions, now you should have 4/5 and 1/5.
Now to generate a chance the 2 events will happen in a row (Like rain and a postponed game) you need to multiply the 2 fractions together so it should come out with 4/25 or 16%
3 0
4 years ago
Read 2 more answers
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