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3 years ago

Please explain the steps

Mathematics

1 answer:

Gnesinka [82]3 years ago

3 0

Answer:

X= -3,-5

Step-by-step explanation:

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Eric purchased three music CDs and a sweatshirt from a band's online store and received a 20% discount. He paid $100 for his pur

emmasim [6.3K]

(3c+s)(100-20)/100=100 multiply both sides by 100

(3c+s)80=10000 divide both sides by 80

3c+s=125 subtract 3c from both sides...

s=125-3c....now let's look at the second situation...

(4c+2s)(100-40)/100=120 multiply both sides by 100

60(4c+2s)=12000 divide both sides by 60

4c+2s=200 divide both sides 2

2c+s=100 subtract 2c from both sides

s=100-2c, and from earlier we saw that s=125-3c, since s=s:

100-2c=125-3c add 3c to both sides

100+c=125 subtract 100 from both sides

c=25, and since s=100-2c

s=50

So cds cost $25.00 and sweatshirts cost $50.00

6 0

3 years ago

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Which statement is used to prove that quadrilateral abcd is a parallelogram

gizmo_the_mogwai [7]

Answer:

Opposite sides must be congruent.

Step-by-step explanation:

Given is a picture of a quadrilateal ABCD

We have to prove that this is a parallelogram.

Recall the properties of parallelogram as

i) diagonals bisect each other

ii) opposite sides parallel

iii) opposite sides congruent

or iv) one pair of opposite sides equal and parallel

We have hence to get opposite sides congruent

So last option is right

5 0

2 years ago

Suppose a and b are both non zero real numbers. Find real numbers c and d such that 1/a+ib= c+id

Thepotemich [5.8K]

$\begin{gathered} c=\frac{a}{a^2+b^2} \\ d=\frac{-b}{a^2+b^2} \end{gathered}$

Explanation

$\frac{1}{a+bi}=c+di$

Step 1

multiplicate by the conjugate

$\begin{gathered} \frac{1}{a+bi}\cdot\frac{a-bi}{a+bi}=\frac{a-bi}{(a+bi)(a-bi)}=\frac{a-bi}{a^2-(bi)^2} \\ \frac{1}{a+bi}\cdot\frac{a-bi}{a+bi}=\frac{a-bi}{(a+bi)(a-bi)}=\frac{a-bi}{a^2-(-b^2)}=\frac{a-bi}{a^2+b^2} \end{gathered}$

notice that

$\begin{gathered} \frac{1}{a+bi}=\frac{a-bi}{a^2+b^2}=\frac{a}{a^2+b^2}-\frac{b}{a^2+b^2}i \\ \frac{a}{a^2+b^2}-\frac{b}{a^2+b^2}i=c+di \\ so \\ \end{gathered}$ $\begin{gathered} c=\frac{a}{a^2+b^2} \\ d=\frac{-b}{a^2+b^2} \end{gathered}$

I hope this helsp you

6 0

1 year ago

Which number is greater tha 9/4

Naddika [18.5K]

Answer:

Step-by-step explanation:

the biggest number gets eaten by the alligator

5 0

3 years ago

The dot plot shows the number of hours, to the nearest hour, that a sample of 5th graders and 7th graders spend watching televis

Black_prince [1.1K]

Answer:

is the median for both of them .

Step-by-step explanation:

6 0

3 years ago

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