Answer:

Step-by-step explanation:
The total cost would be "Y".
"x" is would be "per text message".
12 cents per text message would be .12x.
And then, on top of that, we have to pay $30 per month. ( + 30 )
Put together, the equation should be y = .12x + 30.
The foci of the hyperbola with equation 5y^2-4x^2=20 will be given as follows:
divide each term by 20
(5y^2)/20-(4x^2)/20=20/20
simplifying gives us:
y^2/4-x^2/5=1
This follows the standard form of the hyperbola
(y-k)²/a²-(x-h)²/b²=1
thus
a=2, b=√5 , k=0, h=0
Next we find c, the distance from the center to a focus.
√(a²+b²)
=√(2²+(√5)²)
=√(4+5)
=√9
=3
the focus of the hyperbola is found using formula:
(h.h+k)
substituting our values we get:
(0,3)
The second focus of the hyperbola can be found by subtracting c from k
(h,k-c)
substituting our values we obtain:
(0,-3)
Thus we have two foci
(0,3) and (0,-3)
Answer:
650 cm²
Step-by-step explanation:
Use the formula 2(lw+wh+lh)
Plug in the stuff: 2(5*9+9*20+5*20)=2(45+180+100)=2(325)=650 cm²
And there you go!
Please mark brainliest!