Math Question: z varies jointly with y and the square of x. If x = 3 when y = 6 and z = - 108, find x when z = 16 and y = -2

Varies jointly means y and the square of x are multiplied by a constant to get z. So z=kyx^2. If you substitute in the values given -108=k(6)(3^2) you get -108=54k. To solve divide by 54 and you get k=-2. Now that you know what the constant is you can substitute the second set of numbers to solve for x. So 16= (-2)(-2)(x^2) which gives you 16= 4(x^2). Divide by 4 and you get 4=x^2. Lastly, square root both sides and you get x=+/-2. Don’t forget when you square root you have to consider both the positive and negative solutions.
Answered On 04/11/2020 02:27