Range is the y values or ouputs
domain is inputs or x vvalues
we can use any x value
but at a certain y value, w can't go below that
find thatminimum
find the vertex
for
ax^2+bx+c
the x value of the vertex is
-b/2a
plug that in to the equaiton to get the y value
-b/2a=-(-6)/(2*2)=6/4=3/2
plug that in
2(3/2)^2-6(3/2)-9
2(9/4)-9-9
9/2-18
4.5-18
-13.5
domain=all real numbers
range=from -13.5 to positive infinity
Answer:
I do not know how to read Spanish sorry........
Step-by-step explanation:
Number of weekend minutes used: x
Number of weekday minutes used: y
This month Nick was billed for 643 minutes:
(1) x+y=643
The charge for these minutes was $35.44
Telephone company charges $0.04 per minute for weekend calls (x)
and $0.08 per minute for calls made on weekdays (y)
(2) 0.04x+0.08y=35.44
We have a system of 2 equations and 2 unkowns:
(1) x+y=643
(2) 0.04x+0.08y=35.44
Using the method of substitution
Isolating x from the first equation:
(1) x+y-y=643-y
(3) x=643-y
Replacing x by 643-y in the second equation
(2) 0.04x+0.08y=35.44
0.04(643-y)+0.08y=35.44
25.72-0.04y+0.08y=35.44
0.04y+25.72=35.44
Solving for y:
0.04y+25.72-25.72=35.44-25.72
0.04y=9.72
Dividing both sides of the equation by 0.04:
0.04y/0.04=9.72/0.04
y=243
Replacing y by 243 in the equation (3)
(3) x=643-y
x=643-243
x=400
Answers:
The number of weekends minutes used was 400
The number of weekdays minutes used was 243
