Answer:
Step-by-step explanation:
The equation of a line in slope-intercept form:
m - slope
b - y-intercept → (0, b)
We have the x-intercept = 4 → (4, 0), and y-intercept = 5 → b = 5.
Therefore we have the equation:
Put the coordinates of x-intercept to the equation:
<em>subtract 4m from both sides</em>
<em>divide both sides by (-4)</em>
Finally we have the equation of a line if slope-intercept form:
The standard form:
Convert:
<em>multiply both sides by 4</em>
<em>add 5x to both sides</em>
A: How many text messages would you have to send or receive in order for the plans to cost the same each month?
Answer: 100
Step-by-step:
$.20x100=$20
$40+$20=$60
b: If you send or receive an average of 50 texts each month, which plan would you choose?Why?
Answer: A
Because $.20x50=$10
$40+$10=$50
Answer: 25
Step-by-step explanation:
Answer:
5 hours
Step-by-step explanation:
Let s and w represent hours spent traveling south and west, respectively. The problem statement tells us ...
s + w = 8 . . . . . . total trip time
344s + 351w = 2773 . . . . total mileage (using d = s·t)
By Cramer's rule, we can find the value of s as ...
s = (1(2773) -351(8))/(1(344) -351(1)) = -35/-7 = 5
The plane was heading south for 5 hours.
_____
<em>Comment on Cramer's rule</em>
For the equations ...
ax +by = c
dx +ey = f
The solution for x can be found to be ...
x = (bf-ec)/(bd-ea)
Similarly, the solution for y is ...
y = (cd-fa)/(bd-ea)
