Answer:

u=4

Step-by-step explanation:

r=ks/u²

well put 1 under the 36 so it'll be balance and so can we solve it.

[tex]1 = (\frac{4}{9} )(36) \: \: \: \: \: \: \: \\ {u}^{2} [/tex]

[tex] 1 = (\frac{4}{9} )( \frac{36}{1} ) \\ \: \ \: \: \: \: {u}^{2} [/tex]

now we've already put a 1 on it next we'll multiply both numerator and we'll get 144 next we'll multiply both denominator then we'll get 9. [tex]1 = \frac{144}{9} \\ \: \: \: \: \: \: \: \: \: \\ \: \: \: \: \: \: \: \: {u}^{2} [/tex]

now we already got 144 and 9 next we'll put "u²" for cancelation.

[tex]( {u}^{2}) \: \: 1 = \frac{16}{ {u}^{2} } \: ( {u}^{2} )[/tex]

now we'll multiply u² to 1 then we'll get u²,and u squares on the right side were cancelled.

now we've got u²=16

[tex] {u}^{2} = 16[/tex]

now to find u,go back to extracting the square roots in square roots you should do the extracting to have the product.

[tex] \sqrt{{u}^{2} } = \sqrt{16} [/tex]

now take a look we put square roots both sides so it'll be balance.

so now we extract the "square of u" must gone and the square root of '16' were '4' because 4•4=16

16÷4=4

[tex] \sqrt{ {u}^{2} } = u \\ \\ \sqrt{16} = 4[/tex]

now take a look we'd extract it already now we'll have

| u=4 | u equals to 4