Need help with a math problem. Solve for Z?

try dividing out -3/8

21=-3/8z
21/(-3/8)=z
-56=z

multiply both sides by -8/3

multiply by -8/3

(-8/3)(-3/8)=24/24=1

21X-8/3=-168/3=-56

If the subject is sqrt(20/z + 30/sixteen) = sqrt(510)/12 then z = 12. the important section is to sq. the two factors then (as you wrote it) you are able to have 4*5/z+10*3/sixteen=510/one hundred forty four (the sq. roots disappear and 12 gets squared, 12*12 = one hundred forty four) Now you have an difficulty-free algebra subject the place you are able to desire to subtract 10*3/sixteen from the two factors and then multiply and/or divide on the two factors to get z via itdself.

I am reading this , not as given , but as :-

21 = (- 3/8 ) z

168 = - 3 z

3 z = - 168

z = - 56

21 = -3/8(z)
-3z/8 = 21
3z = -8(21)
z = -168/3
z = -56

an easy way to understand is:
1. multiply 21 with 8
2. then divide it with 3
3. put a negative sign in front of the answer (or multiply with -1)

good luck!

multiply both sides by -1
-21=3/8z
divide both sides by 3
-7=1/8z
times both sides by 8
-56=8/8z
-56=z

Divide 21 by 8/-3 (because 8/-3 is the reciprocal of -3/8.

21/ 8/-3 = z

168/-3 = z

x = 56

Rae: Excuse me for giving you a long answer to this problem. This is to insure you fully know a cardinal rule of math and how one uses it to solve problems like your's. One can change signs: -to+ & +to-, add, subtract, multiply, and divide one side of any equation with any number and the equation will remain correct as long as one does the exact same thing to the other side of the equation. Example: 2+2=4, 2/2+2/2=4/2, etc.1. Multiplying both sides of your equation by the( - )sign and swapping places we get 3/8Z= -21. We now divide both sides by 3/8: 3/8divided by 3/8=1Z or simply Z. Now Z = - 21/(3/8). Now we cn divide 8 by 3 and get .375, we can now divide -21 by .375 and get -56 for our answer; however we get the same by simply multiplying -21 by 8/3( the reciprocal of 3/8) =-168/3=-56. The next time you see a problem similar: Example- 5/3 Y =30, you can quickly state Y=-30 x 3/5, Y =-90/5=-19. Hope this helps