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Katyanochek1 [597]
2 years ago
5

Evaluate the expression: 5x – y when x = -4 and y= -2 marked as brainliest :)

Mathematics
1 answer:
sp2606 [1]2 years ago
7 0

It's a good idea to get into the habit of

using parenthses when substituting

numbers in for variables.

Since x = -4 and y = -2, 5x - y is 5(-4) - (-2).

Now, 5(-4) is -20 and minus a negative 2

can be thought of as plus a positive 2.

So we have (-20) + (+2) which equals -18.

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Someone please help !! I don’t know what I’m doing with this !!
dimulka [17.4K]

Answer:

  a) d(sinh(f(x)))/dx = cosh(f(x))·df(x)/dx

  b) d(cosh(f(x))/dx = sinh(f(x))·df(x)/dx

  c) d(tanh(f(x))/dx = sech(f(x))²·df(x)/dx

  d) d(sech(4x+2))/dx = -4sech(4x+2)tanh(4x+2)

Step-by-step explanation:

To do these, you need to be familiar with the derivatives of hyperbolic functions and with the chain rule.

The chain rule tells you that ...

  (f(g(x)))' = f'(g(x))g'(x) . . . . where the prime indicates the derivative

The attached table tells you the derivatives of the hyperbolic trig functions, so you can answer the first three easily.

__

a) sinh(u)' = sinh'(u)·u' = cosh(u)·u'

For u = f(x), this becomes ...

  sinh(f(x))' = cosh(f(x))·f'(x)

__

b) After the same pattern as in (a), ...

  cosh(f(x))' = sinh(f(x))·f'(x)

__

c) Similarly, ...

  tanh(f(x))' = sech(f(x))²·f'(x)

__

d) For this one, we need the derivative of sech(x) = 1/cosh(x). The power rule applies, so we have ...

  sech(x)' = (cosh(x)^-1)' = -1/cosh(x)²·cosh'(x) = -sinh(x)/cosh(x)²

  sech(x)' = -sech(x)·tanh(x) . . . . . basic formula

Now, we will use this as above.

  sech(4x+2)' = -sech(4x+2)·tanh(4x+2)·(4x+2)'

  sech(4x+2)' = -4·sech(4x+2)·tanh(4x+2)

_____

Here we have used the "prime" notation rather than d( )/dx to indicate the derivative with respect to x. You need to use the notation expected by your grader.

__

<em>Additional comment on notation</em>

Some places we have used fun(x)' and others we have used fun'(x). These are essentially interchangeable when the argument is x. When the argument is some function of x, we mean fun(u)' to be the derivative of the function after it has been evaluated with u as an argument. We mean fun'(u) to be the derivative of the function, which is then evaluated with u as an argument. This distinction makes it possible to write the chain rule as ...

  f(u)' = f'(u)u'

without getting involved in infinite recursion.

7 0
2 years ago
Mason has 29.8 ounces of peanuts. He eats 5 ounces of the peanuts. Then he divides the rest of the peanuts equally among 4 frien
Snowcat [4.5K]

Alright, so the first step we are gonna do to solve this problem is subtract since Mason ate 5 ounces of the peanuts and so, we need to subtract 5 out of 29.8.

29.8 - 5 = 24.8

So, now there is 24.8 ounces.

Now we move onto the next step which is division. As you can see in the question it says "Then he divides the rest of the peanuts equally among 4 friends."

24. 8 ÷ 4 = 6.2

Since the answer is supposed to be a decimal..that's your answer!

So overall, each of Mason's friends get 6.2 ounces of peanuts.

Hope this helps!

If you are needing any more help, comment below this comment for any contact of mine. I'll be glad to help!

- Kana

7 0
3 years ago
Max,mia and jadea are sharing six pancakes equally . What fraction of the pancakes dose each child get?
tiny-mole [99]

Answer:

2/6 each

Step-by-step explanation:

6 pancakes divided by the 3 kids equals 2, so each child will get 2 pancakes.

7 0
3 years ago
Read 2 more answers
Each side of a square x units long is decreased by 9 units. which expression represents the area of the new square in square uni
Vinil7 [7]

Answer:

a= (x-9)2

a=x2-18x+81

7 0
2 years ago
If parallelogram ABCD with vertices A(-5,1) B(-4,1) C(-6,4) and D (-3,6) was reflected about the y-axis, what would be the coord
Nikolay [14]
A(5,1) B(4,1) C(6,4) D(3,6)
6 0
3 years ago
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