Anonymous

# Can someone please solve for V in this equation?

600 / ( V + 30 ) + 600 / ( V - 30 ) = 4.5

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600/(v+30) + 600/(v-30) = 4.5

600[1/(v+30) + 1(v-30)] = 4.5

multiply with (v^2 - 900)

600[v-30 + v + 30] = 4.5(v^2-900)

600[2v] = 4.5v^2 - 4050

4.5v^2 - 1200v - 4050 = 0

multiply with 2

9v^2 - 2400v - 8100 = 0

9v^2 - 2430v + 30v - 8100 = 0

9v(v - 270) + 30(v - 270) = 0

(v-270)(9v + 30) = 0

v = 270 or -10/3

• by putting both numbers under 1, like this,

1/(600/(v+30)+600/(v-30))=1/(4.5)

we get:

(v+30)/600+(v-30)/600=1/4.5

since the denominator is the same,

((v+30)+(v-30))/600=1/4.5

2v/600=1/4.5

*600 on both sides results:

2v=600/4.5

then divide by 2 to get:

v=600/9

v=66 2/3

• 600 / (V+30) + 600 / (V-30) = 4.5

Multiply by (V+30)(V-30) = V² – 900

600(V-30) + 600(V+30) = 4.5 (V² – 900)

600V-18000 + 600V +18000 = 4.5 V² – 4050

1200 V = 4.5 V² – 4050

4.5 V² -1200V – 4050

Use –b ± √ [( b )² – 4(ac) ] / 2a

-(-1200) ±√ [140000+72900] / 9

1200 ± 1230 / 9

V= -3.33

V= 270

• [600(V-30) + 600(V+30)] / (V+30)(V-30) = 4.5

600V - 18000 + 600V + 18000 = 4.5(V^2 - 900)

0 = 4.5V^2 - 1200V - 4050

Solve the quadratic equation using the formula.