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mel-nik [20]
2 years ago
15

Mr. Akika has 49 21 cent and 31 cent stamps all told. The stamps are worth $13.39. how many of each kind of stamps does he have?

Mathematics
1 answer:
Lana71 [14]2 years ago
4 0

Mr Akika has 18  21-cent stamp and 31 31-cent stamp.  

He has 49 21-cent and 31-cent stamps all told.

let

x = number of 21 cent stamp

y = number of 31 cent stamp

Therefore,

<h3>Total number of stamp:</h3>
  • x + y  = 49
<h3>Total cost of stamp:</h3>
  • 21x + 31y = 1339

Therefore,

x + y = 49

21x + 31y = 1339

21x + 21y = 1029

10y = 310

y = 310 / 10

y = 31

Therefore,

x = 49 - 31

x = 18

Therefore, Mr Akika has 18  21-cent stamp and 31 31-cent stamp.  

learn more on system of equation: brainly.com/question/1369852?referrer=searchResults

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g The tangent plane to z=f(x,y) at the point (1,2) is z=5x+2y−10. (a) Find fx(1,2) and fy(1,2). fx(1,2)= Number fy(1,2)= Number
murzikaleks [220]

Answer:

The values for Fx(1,2) and Fy(1,2) are 5 and 2 respectively.

Approximation at points (1.1,1.9) is 0.7

Step-by-step explanation:

Given:

Tangent plane to  a surface z=5x+2y-10 as the function at point (1,2)

To find :

f(x,y) at (1,2)

partial derivatives of function w.r.t. (x and y) and value of that function at given points.

Solution:(refer the attachment also)

Now we know that

the equation of tangent plane at given points to the surface is given by,

f(x1,y1,z1) and z=f(x,y)

z-z1=Fx(x1,y1)*(x-x1)+Fy(x1,y1)*(y-y1)

here Fx(x1,y1) and Fy(x1,y1) are the partial derivatives of x and y.

now

taking partial derivative w.r.t. x we get

Fx(x1`,y1)=\frac{d}{dx} (5x+2y-10)

=5.

Then w.r.t y we get

Fy(x1,y1)=

\frac{d}{dy}(5x+2y-10)

=2.

The values for Fx(1,2) and Fy(1,2) are 5 and 2 respectively.

Using the Linearization or linear approximation we get

L(x,y)=f(x1,y1)+Fx(x,y)*(x-x1)+Fy(x,y)(y-y1)

=-1+5(x-1)+2(y-2)

=5x+2y-10

Approximation at F(1.1,1.9)

=5(1.1)+2(1.9)-10

=5.5+3.8-10

=0.7

Approximation at points (1.1,1.9) is 0.7

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