How do I solve -0.4r=16?

r = -40

Step-by-step explanation:

1. Move constants to the other side of the equation

r = 16/-.04

2. Simplify (by calculator)

You can use a calculator and plug in 16/-.04

r = -40

2. Simplify (by fraction)

You can turn -.4 into a fraction.

-.04 = - 4/10

r = 16/-(4/10)

r = 16*10/-4

r = -40

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

answer:

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