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Oksanka [162]
3 years ago
11

Solve the system of equations using the substitution method.

Mathematics
1 answer:
Katena32 [7]3 years ago
3 0
        4x+5y=7
         y=3x+9

1)      4x+5(3x+9)=7                 2)        y=3(-2)+9
                                                             y= -6 +9 
         4x+15x+45=7                               y=3                                                     
         19x+45=7
          19x= -38
             x= -2
x is -2 and y is 3
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I need help,I need to use substitution but I don't know how
lions [1.4K]

If y=x+6 and y=-2x-3, then you can replace y in either equation with the equivalent expression given by the other equation. In this case, you have

x+6=-2x-3

and you can solve for x.

x+2x+6-6=-2x+2x-3+6\implies3x=3\implies\dfrac{3x}3=\dfrac33\impliesx=1

Then y=1+6=7.

For the second system, you can write

5x-y=-5\implies 5x-5x-y=-5-5x\implies-y=-5-5x

\implies-(-y)=-(-5-5x)\implies y=5+5x

Then substitute this into the second equation and you get

3x-6(5+5x)=24\implies3x-30-30x=24\implies-27x-30+30=24+30

\implies-27x=54\implies x=2

so that

y=5+5(2)=15

8 0
4 years ago
HELP ME PLS.......................TY
Tom [10]
M is correct, at the end your answer will be 5m
5 0
3 years ago
Please help!!!!!!!! what is the answer
hichkok12 [17]

Answer:

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Step-by-step explanation:

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8 0
2 years ago
Read 2 more answers
Find the absolute maximum and absolute minimum values of f on the given interval.
anyanavicka [17]

The question is missing parts. Here is the complete question.

Find the absolute maximum and absolute minimum values of f on the given interval.

f(x)=xe^{-\frac{x^{2}}{32} } , [ -2,8]

Answer: Absolute maximum: f(4) = 2.42;

              Absolute minimum: f(-2) = -1.76;

Step-by-step explanation: Some functions have absolute extrema: maxima and/or minima.

<u>Absolute</u> <u>maximum</u> is a point where the function has its greatest possible value.

<u>Absolute</u> <u>minimum</u> is a point where the function has its least possible value.

The method for finding absolute extrema points is

1) Derivate the function;

2) Find the values of x that makes f'(x) = 0;

3) Using the interval boundary values and the x found above, determine the function value of each of those points;

4) The highest value is maximum, while the lowest value is minimum;

For the function given, absolute maximum and minimum points are:

f(x)=xe^{-\frac{x^{2}}{32} }

Using the product rule, first derivative will be:

f'(x)=e^{-\frac{x^{2}}{32} }(1-\frac{x^{2}}{16} )

f'(x)=e^{-\frac{x^{2}}{32} }(1-\frac{x^{2}}{16} ) = 0

1-\frac{x^{2}}{16}=0

\frac{x^{2}}{16}=1

x^{2}=16

x = ±4

x can't be -4 because it is not in the interval [-2,8].

f(-2)=-2e^{-\frac{(-2)^{2}}{32} }=-1.76

f(4)=4e^{-\frac{4^{2}}{32} }=2.42

f(8)=8e^{-\frac{8^{2}}{32} }=1.08

Analysing each f(x), we noted when x = -2, f(-2) is minimum and when x = 4, f(4) is maximum.

Therefore, absolute maximum is f(4) = 2.42 and

absolute minimum is f(-2) = -1.76

8 0
3 years ago
How can you divide 512 Dollars between two people So that one person can get $20 more than the other
Naya [18.7K]

Step-by-step explanation:

It is possible

One person will get 246 while the other will get 266 = 512

6 0
4 years ago
Read 2 more answers
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