f = (f1 f2) / (f1 + f2)
f(f1 + f2) = f1 f2
f f 1 + f f 2 = f1 f 2
f1 f2 - f f2 = f f1
f2 (f1 - f) = f f1
f2 = (f f1) / (f1 - f) <==== solution
Answer:
Number of photos = 3 * minutes
Step-by-step explanation:
3 less than the quotient of a number y and 4
3 < y / 4
3 < y/4
x 4 x 4
12 < y
Answer:
Step-by-step explanation:
y - 3 = (-1/2)(x - 2)
Solve 8x-4y+9=0 for y so as to find the slope of this given line:
8x + 9 = 4y, or y = 2x + 9/4. The slope of the given line is 2. The slope of any line perpendicular to this one is the negative reciprocal of 2, which is -1/2.
Use the point-slope formula: y - k = m(x - h ). (h, k) is (2, 3) and m is -1/2.
Then we have: y - 3 = (-1/2)(x - 2)
