√21 - √5x-4 = 0

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√21 - √5x-4 = 0 First square both values that are attached to the square root function. (√21)^2 - (√5x-4)^2 = 0 21 - 5x - 4 = 0 Then combine the like terms 21 and - 4 to get 17. 17 - 5x = 0 Move the - 5x on the left side of the equation to the right side to isolate your variable, x and to remove the (-) negative value attached to your x. 17 = 5x Then, divide both sides by 5 to make your x value equal to one. 17/5 = 5x/5 x=17/5 or x=3.5

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