Answer:
x2 +2x−xy when x = 250 and y = −120 ... sic Algebra: Patterns and Equations (13:18)
Step-by-step explanation:
Answer: 3 miles per hour
<u>Step-by-step explanation:</u>
Use the formula "distance (d) = rate (r) x time (t)" to create a system of equations.
Let "r" represent the rate they are rowing
Let "c" represent the current
time rate distance <u>EQUATION</u>
Downstream: 4 hours r + c 40 miles 4(r + c) = 40
Upstream: 10 hours r - c 40 miles 10(r - c) = 40
Distribute, then eliminate r to solve for c:
Down: 4r + 4c = 40 → 5(4r + 4c = 40) → 20r + 20c = 200
Up: 10r - 10c = 40 → -2(10r - 10c = 40) → <u>-20r + 20c</u> =<u> -80</u>
40c = 120
<u> ÷40 </u> <u>÷40 </u>
c = 3
.70 * x = 9.1
.70/.70 * x = 9.1/.70
x = 13
<em><u>Question:</u></em>
If y varies inversely with the square of r, what is the constant of proportionality when y =10 and r = 5?
<em><u>Answer:</u></em>
The constant of proportionality is 250
<em><u>Solution:</u></em>
Given that,
y varies inversely with the square of r
Which means,
Where, "k" is constant of proportionality
Subtitute y = 10 and r = 5
Thus the constant of proportionality is 250
