R=square root of u squared plus v squared divided by m and u and v are positive.Find u when r=3,v=6 and m=5

the problem with language is it imprecise. That is why the French Academy in the 1700's went to symbols.

R = √(u^2+v^2)/m

so, just plug in the numbers:
3 = √(u^2+6^2)/5
15 = √(u^2+36)
Now square both sides to get
u^2+36 = 225
u^2 = 189
u = ±√189 = ±3√21

To find the value of u when r=3, v=6, and m=5 in the equation R = √(u² + v²)/m, we can follow these steps:

Step 1: Substitute the given values into the equation:
3 = √(u² + 6²)/5

Step 2: Simplify the equation:
Multiply both sides of the equation by 5:
15 = √(u² + 6²)

Step 3: Square both sides of the equation to eliminate the square root:
Square the left side: (15)² = 225
Square the right side: (√(u² + 6²))² = u² + 36

Now, our equation becomes:
225 = u² + 36

Step 4: Rearrange the equation to isolate u²:
Subtract 36 from both sides: 225 - 36 = u²
Simplify: 189 = u²

Step 5: Take the square root of both sides to solve for u:
√189 = u
Simplify: u ≈ 13.74

Therefore, when r = 3, v = 6, and m = 5, the value of u is approximately 13.74.