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zheka24 [161]
2 years ago
8

Solve the system of equations x + y = 0 and x + 9y= -48 by combing the eqatuons

Mathematics
1 answer:
lidiya [134]2 years ago
7 0

Answer:

x = 6

y = -6

Step-by-step explanation:

x + y = 0 (Multiply by -1)

x + 9y= -48

-x - y = 0

x + 9y= -48

8y = -48

y = -6

x + y = 0

x - 6 = 0

x = 6

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Explain why the function is discontinuous at the given number
Blizzard [7]
For f to be continuous at x=5, we need to have

\displaystyle\lim_{x\to5}f(x)=f(5)

Note that x\to5 means that x\neq5, but that x is *approaching* 5. We're told that for x\neq5, we have

f(x)=\dfrac{x^2-5x}{x^2-25}

We can write

\dfrac{x^2-5x}{x^2-25}=\dfrac{x(x-5)}{(x+5)(x-5)}=\dfrac x{x+5}

and the limit would be

\displaystyle\lim_{x\to5}\frac x{x+5}=\dfrac5{5+5}=\dfrac5{10}=\dfrac12\neq1=f(5)

and so f is discontinuous.
5 0
3 years ago
What is the opposite of 48? <br> A. –84 B. –48 C. 48 D. 84
Aleksandr [31]
It's B Dat is dat is right
7 0
2 years ago
zolas mother spends 39 minutes braiding zolas hair she finishes at 7:52 what time did she start braiding zolas hair
Mumz [18]
The answer would be 7:13
8 0
2 years ago
Read 2 more answers
which expressions are equivalent to the first one? I don't understand how to determine that so please explain. Thanks!​
coldgirl [10]

9514 1404 393

Answer:

  (a) -(x+7)/y

  (b) (x+7)/-y

Step-by-step explanation:

There are several ways you can show expressions are equivalent. Perhaps the easiest and best is to put them in the same form. For an expression such as this, I prefer the form of answer (a), where the minus sign is factored out and the numerator and denominator have positive coefficients.

The given expression with -1 factored out is ...

  \dfrac{-x-7}{y}=\dfrac{1(x+7)}{y}=\boxed{-\dfrac{x+7}{y}} \quad\text{matches A}

Likewise, the expression of (b) with the minus sign factored out is ...

  \dfrac{x+7}{-y}=\boxed{-\dfrac{x+7}{y}}

On the other hand, simplifying expression (c) gives something different.

  \dfrac{-x-7}{-y}=\dfrac{-(x+7)}{-(y)}=\dfrac{x+7}{y} \qquad\text{opposite the given expression}

__

Another way you can write the expression is term-by-term with the terms in alpha-numeric sequence (so they're more easily compared).

  Given: (-x-7)/y = (-x/y) +(-7/y)

  (a) -(x+7)/y = (-x/y) +(-7/y)

  (b) (x+7)/(-y) = (-x/y) +(-7/y)

  (c) (-x-7)/(-y) = (x/y) +(7/y) . . . . not the same.

__

Of course, you need to know the use of the distributive property and the rules of signs.

  a(b+c) = ab +ac

  -a/b = a/(-b) = -(a/b)

  -a/(-b) = a/b

__

<u>Summary</u>: The given expression matches (a) and (b).

_____

<em>Additional comments</em>

Sometimes, when I'm really stuck trying to see if two expressions are equal, I subtract one from the other. If the difference is zero, then I know they are the same. Looking at (b), we could compute ...

  \left(\dfrac{-x-7}{y}\right)-\left(\dfrac{x+7}{-y}\right)=\dfrac{-y(-x-7)-y(x+7)}{-y^2}\\\\=\dfrac{xy+7y-xy-7y}{-y^2}=\dfrac{0}{-y^2}=0

Yet another way to check is to substitute numbers for the variables. It is a good idea to use (at least) one more set of numbers than there are variables, just to make sure you didn't accidentally find a solution where the expressions happen to be equal. We can use (x, y) = (1, 2), (2, 3), and (3, 5) for example.

The given expression evaluates to (-1-7)/2 = -4, (-2-7)/3 = -3, and (-3-7)/5 = -2.

(a) evaluates to -(1+7)/2 = -4, -(2+7)/3 = -3, -(3+7)/5 = -2, same as given

(b) evaluates to (1+7)/-2 = -4, (2+7)/-3 = -3, (3+7)/-5 = -2, same as given

(c) evaluates to (-1-7)/-2 = 4, different from given

3 0
2 years ago
A man divided $9,000 among his wife, son, and daughter. The wife received twice as much as the daughter, and the son received $1
monitta

Answer:

Q1:

Share of the daughter (x):

2x + x + x + $1,000 = $9,000

4x = $8,000

x = $2,000

Share of the wife:

= 2($2,000)

=  $4,000

Share of the son:

= $2,000 + $1,000

= $3,000

Answer: wife, $4,000; son, $3,000; daughter, $2,000

Q2:

= 1/2x + $1,000

Answer: 1/2x + $1,000: expression for share of the son

Proof (the wife shares $4,000):

Share of wife (x):

x + 1/2x + 1/2x + $1,000 = $9,000

2x = $8,000

x = $4,000

Step-by-step explanation:

hope it helps!

6 0
3 years ago
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