Solve the following problem: (u + 3)/8 = 5/ (u -3)

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have to find the values of x that satisfy the equation (u+3)/8 = 5/( u-3)

(u+3)/8 = 5/( u-3)

multiply both sides by (u - 3)

=> (u +3 )(u - 3) = 5*8

=> u^2 - 3^2 = 40

=> u^2 - 9 = 40

=> u^2 = 40+9

=> u^2 = 49

=> u = -sqrt 49 and sqrt 49

=> u = -7 and 7

Therefore u can be equal to 7 and -7.

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hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

(u+ 3)/8 = 5/(u-3).

To solve the equation, we need to cross multiply.

==> (u+3)*(u-3) = 8*5

==> (u+3)(u-3) = 40.

Now we will expand the brackets.

==> u*u + 3*u + u*-3 + 3*-3 = 40

==> u^2 + 3u - 3u - 9 = 40

Now we will reduce similar terms.

==> u^2 - 9 = 40

Now we will add 9 to both sides.

==> u^2 = 40+9

==> u^2 = 49.

Now we will take the root of both sides.

==> u= +- 7.

Then, there are two possible values for u that satisfies the equation.

==> u = { -7, 7}

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