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3 years ago

HELP PLZ!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Mathematics

2 answers:

Maurinko [17]3 years ago

5 0

Answer:

D. $x=-5,y=\frac{5}{4}$

Step-by-step explanation:

$\begin{bmatrix}5x+4y=-20\\ 5x+12y=-10\end{bmatrix}$

Subtract Equation 2 - Equation 1:

$5x+12y=-10\\-\\\underline{5x+4y=-20}\\8y=10$

Divide both sides by 8:

$\frac{8y}{8}=\frac{10}{8}$

$y=\frac{5}{4}$

Substitute $y=\frac{5}{4}$ into Equation 1:

$5x+4y=-20$

$5x+4\times \frac{5}{4}=-20$

$5x+5=-20$

Subtract 5 from both sides:

$5x+5-5=-20-5$

$5x=-25$

Divide both sides by 5:

$\frac{5x}{5}=\frac{-25}{5}$

$x=-5$

Bas_tet [7]3 years ago

4 0

Answer:

Step-by-step explanation:

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Y=log(x-3) what would be the base?

timurjin [86]

By definition, if :

$a^y = b$

$y = log_a b$

We highlight the following elements:

a = Base of the logarithm;
b = logarithmand or antilogarithm
y = logarithm

Therefore:

Note that since the base was not specified, we know that it is equal to 10.

$y = log_a b$
$y = log_{10} (x-3)$
$10^y = (x-3)$

Answer:

Base of the logarithm = 10

4 0

3 years ago

Mary has a collection of nickels and quarters for a total of $4.90. If she has 42 coins in total, how many of each kind are ther

damaskus [11]

Answer:

14 quarters and 28 nickels

Step-by-step explanation:

System of Equations where x = number of quarters and y = number of nickels

(1) equation with value of each coin

0.25(x)+0.05(y) = 4.90

(2) total number of coins

x + y = 42

Solve system of equations using either substitution or elimination

(elimination multiplying equation 2 by -0.5)

.25(x) + 0.05(y) = 4.90

-0.05(x) - 0.05(y) = 42 * (-0.05)

(3) Resulting equation

.20(x) = 2.8

x = 14

plug x into equation 2

14 + y = 42

y = 28

There are 14 quarters and 28 nickels in Mary's collection.

5 0

3 years ago

When y=-2, what kind of line does it have horizontal or vertical

Rashid [163]

Answer: Horizontal

Step-by-step explanation: The equation y = -2 can be thought of as y = 0x - 2. So our line has a slope of 0 and a y-intercept of -2.

To graph it, we start with the y-intercept, down 2 units on the y-axis. Now, if the slope of a line is 0, then the line must be flat or horizontal.

So we just draw a horizontal line through the y-intercept of -2.

In fact, when the equation of any line reads y = a number, it's graph will always be a horizontal line. For example, y = 3, y = -10, y = -8 and so on.

Image provided below.