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2 years ago

If y varies directly with x and y=20.4 when x=6, find the value of y when x=-5?

Mathematics

2 answers:

Svetlanka [38]2 years ago

8 0

Answer:

A. Y=17

Step-by-step explanation:

Hope this helps

a_sh-v [17]2 years ago

4 0

Answer:

y=-17

Step-by-step explanation:

y=mx

20.4=m×6

20.4÷6=m

3.4=m

y=3.4×-5

y=-17

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There are 31 coins of dimes and quarters. If the number of dimes is 5 more than the number of quarters, how many quarters are th

emmasim [6.3K]

Answer:

13 Quarters and 18 Dimes

Step-by-step explanation:

Let D and Q stand for the numbers of Dimes(D) and Quarters(Q). Give x and y a break, and make it easier to remember which is which.

D + Q = 31

D = Q + 5

Therefore:

D + Q = 31

(Q+5) + Q = 31

2Q + 5 = 31

2Q = 26

Q = 13

Then D = (13+5) or 18

================

Check:

D + Q = 31 ?

18 + 13 = 31 YES

----------------------

D = Q + 5 ?

18 = 13 + 5 YES

5 0

2 years ago

What is an equation of the line that passes through the points (0, -7) and (-8, 3)?

avanturin [10]

Answer (assuming it can be in slope-intercept form):

$y = -\frac{5}{4} x-7$

Step-by-step explanation:

1) First, find the slope of the line by using the slope formula, $m = \frac{y_2-y_1}{x_2-x_1}$ . Substitute the x and y values of the given points into the formula and solve:

$m = \frac{(3)-(-7)}{(-8)-(0)}\\m = \frac{3+7}{-8-0} \\m = \frac{10}{-8} \\m = -\frac{5}{4}$

So, the slope is $-\frac{5}{4}$ .

2) Now, use the point-slope formula $y-y_1 = m (x-x_1)$ to write the equation of the line in point-slope form. Substitute real values for the $m$ , $x_1$ , and $y_1$ in the formula.

Since $m$ represents the slope, substitute $-\frac{5}{4}$ in its place. Since $x_1$ and $y_1$ represent the x and y values of one point the line intersects, choose any one of the given points (either one is fine, it will equal the same thing at the end) and substitute its x and y values into the formula as well. (I chose (0, -7), as seen below.) Then, isolate y to put the equation in slope-intercept form and find the following answer:

$y-(-7) = -\frac{5}{4} (x-(0))\\y + 7 = -\frac{5}{4} x\\y = -\frac{5}{4} x-7$