plez help me this count as my final?

Question

The speed limit on a certain interstate highway is 70 miles per hour. Drivers caught speeding on the highway must pay a fine; the fine is caluculated using the following formula:
F= X^2-5X
WHERE F IS THE AMOUNT OF THE FINE, IN DOLLARS AND X IS THE NUMBER OF MILES PER HOUR (MPH) BY WHICH THE DRIVER'S SPEED EXCEEDED THE SPEED LIMIT.

pLEASE ANSWER THE FOLLOWING QUESTIONS.

* iF U WERE CAUGHT DRIVING 90 MPH ON THE INTERSATE, WHAT FINE WOULD U PAY

* WHAT SPPED WOULD A PERSON HAVE BEEN TRAVELING ON THE INTERSTATE IF HE OR SHE HAD TO PAY A FINE OF $176

* iN THE LAST SIX MONTHS, ANNE HAS RECIEVED TICKETS FOR DRIVING 85 MPH, 102 MPH, AND 99 MP. wHAT DOMAIN AND RANGE FOR THIS RELATION

CAN SOME EXPLAIN TO ME WHY THE DOMAIN IS 85,99,102 BECAUSE SOMEONE ELSE GAVE ME 15,29,32 WHICH IS RIGHT?

Answer 1

1)

F = 20^2 - 5(20)
= 400 - 100
=300

Therefore, you would pay $300 if caught driving at 90 MPH.

2) 176 = x^2 - 5x

0 = x^2 - 5x - 176

Use quadratic formula...

x = [-b +/- sqrt (b^2 - 4ac)] / 2a
= 5 +/- sqrt ((-5)^2-4(1)(-176))/2
= 5 +/- sqrt (25 + 704)/2
= 5 +/- 27/2

Take the positive root:

(5+27) /2 = 16

16 + 70 = 86, therefore, the driver must drive at 86 MPH to receive a fine of $176.



3)

Domain {85,99,102, x E R}
Range {150,696,864, y E R}

Answer 2

90mph: $300 fine
$176 fine: 86 mph
domain = 15 mph to 32 mph; range = $150 to $864


1. X = 90 - 70 = 20, so Fine = 20^2 - 5*20 = 400 - 100 = 300

2. 176 = x^2 - 5x so: x^2 - 5x - 176 = 0 which has roots of -11 and 16. Assuming going 59 is not going slowly enough to get a speeding ticket here (yeah, believe it or not, the police call it a speeding ticking whether going too fast or below the highway's legal minimum!), only the root of 16 matters so that person's speed was 70 mph + 16 mph = 86 pmh.

3. Domain is the range (sorry! consider that as English, not "Math") of input values to an equation. The equation takes the speed in excess of 70 mph, not the absolute speed, so one subtracts 70 mph from the lowest and highest values. Range ("Math" not English) is the range (oh, you get it by now) of output values and so is in dollars and is the outcome of the three values given. In practice, that's the two ends of the domain we found, but, since it's not a linear equation, a more general situation might require finding results for all values given in the list. And the domain and range for the equation, not her three tickets, is different yet.

Answer 3

The first answer is actually:
X = 90-70 = 20 excess speed
F = (20*20) - 5*20 = 400-100 = $300

Answer 4

f = 20² - 5(20) = 400 - 100 = $300

176 = x² - 5x
x² - 5x - 176 = 0
(x - 16)(x + 11) = 0
x = 16, so speed = 70+16 = 86 mph.

domain {85,99,102}
range {150,696,864}

Answer 5

http://www.coolmath.com

F= (90-70)^2 - 5(90-70)

176 = (x - 70)^2 - 5(x-70)