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The credit remaining on a phone card (in dollars) is a linear function of the total calling time made with the card (in minutes)

saw5 [17]

Answer: $19.6

Step-by-step explanation:

Linear function: f(x)=mx+c

, where m= rate of change in f(x) with respect to x.

c = Initial value.

Let c = Initial value of card , m= Charge per minute

x= Number of minutes calling time.

Then, 25.06= 38m+c (i)

21.03=69m+c (ii)

Eliminate (ii) from (i)

$4.03=-31m\\\\\Rightarrow\ m=\dfrac{4.03}{-31}\\\\\Rightarrow\ m=-0.13$

Put m in (i) , we get

$25.06= 38(-0.13)+c\\\\\Rightarrow\ 25.06=-4.94+c\\\\\Rightarrow\ c=25.06+4.94\\\\\Rightarrow\ c=30$

i.e. f(x)=-0.13x+30

if x=80 then

f(80)= -0.13(80)+30

=-10.4+30

=19.6

Hence, the remaining credit after 80 minutes of calls = $19.6

7 0

3 years ago

If y varies inversely as x, find the constant of variation if y=36 when x=9

Jobisdone [24]

Answer:

k = 324

Step-by-step explanation:

Y varies inversely as x

Let k be the constant of variation

Y = k/ x

Y= 36 and x= 9

Substitute the value of Y and x

36 = k/9

Make k the subject of the formula

k= 36*9

k =324

5 0

3 years ago

The length of a rectangle is twice its width. if the perimeter of the rectangle is 36 cm , find its area.

Brut [27]

L = Length
W = Width

L x W = area
Length = 2w

Lets find the width by solving for w.
2w + w = 36
3w = 36
3w/3 = 36 / 3
w = 12

So
L = 2 x 12 = 24
W = 12
L X W = area
24 x 12 = 288 cm^2

6 0

3 years ago

What are the postulates for congruent triangles

Delvig [45]

Hi there!

There are 5 ways to find if two triangles are congruent :

SSS, SAS, ASA, AAS & HL

1. SSS (Side, Side, Side)

Means that we have two triangles with 3 sides equal.

⇒ If 3 sides of one triangle are equal to 3 sides of another triangle, the triangles are congruent.

2. SAS (Side, Angle, Side)

Means that we have two triangles where we know 2 sides and the included angle are equal.

⇒ If 2 sides and the includent angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.

3. ASA (Angle, Side, Angle)

Means that we have two triangles where we know 2 angles and the included side are equal.

⇒ If 2 angles and the included side of one triangle are equal to the corresponding angles and side of another triangle, the triangles are congruent.

4. AAS (Angle, Angle, Side)

Means thant we have two triangles where we know 2 angles and the non-included side are equal.

⇒ If 2 angles and the non-included side of one triangle are equal to the coresponding angles and side of another triangle, the triangles are congruent.

5. HL (Hypotenuse, leg)

** This one only applies to right-angled triangles.**

Hypotenuse: The longest side of a right-angled triangle.

Legs: The other 2 sides of the right-angled triangle.

Means we have two right-angled triangles with the same length of hypotenuse and the same length for one of the other 2 legs (it doesn't matter which leg since the triangles could be rotated).

⇒ If the hypotenuse and one leg of one right-angled triangles are equal to the corresponding hypotenuse and leg of another right-angled triangles, the two triangles are congruent.

There you go! I really hope this helped, if there's anything just let me know! :)

7 0

3 years ago

At pizza express it takes 6 cups of cheese to make 15 pizzas. At perfect pizza it takes 4 cups of cheese to make 6 pizzas. If th

rodikova [14]

Pizza Express has a larger constant of proportionality than Perfect Pizzas because 1.6 > 1.5

15/6 6/4

Simplify

5/3 > 3/2

PE: 5/3 or 1.6

PP: 3/2 or 1.5

I had this on my math test

4 0

4 years ago