What is the inversion operation of this problem. z-8=91/3

1 answer:

wel3 years ago

5 0

It is a good idea to look at the operations performed on the variable from the point of view of order of operations. Here, the value 8 is subtracted from z.

Addition is the inverse operation of subtraction. To undo the subtraction of 8, you must add 8.

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Of course, anything you do to one side of the equation must also be done to the other side. That's what keeps the sides equal.
.. z -8 +8 = 91/3 +8
.. z = (91 +24)/3
.. z = 115/3

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John and Tim are looking at the equation the square root of the quantity of 3 times x minus 4 equals square root of x . John say

IgorC [24]

The equation is
3x - 4 = sqrt(x)
where 'sqrt' is shorthand for 'square root'

Let's solve the equation. To do so, we square both sides. Then we get everything to one side
3x - 4 = sqrt(x)
(3x - 4)^2 = (sqrt(x))^2
9x^2 - 24x + 16 = x
9x^2 - 24x + 16-x = x-x
9x^2 - 25x + 16 = 0

Now use the quadratic formula. See the attached image for those steps.

After using the quadratic formula the two possible solutions are x = 1 or x = 16/9

We need to check each possible solution to see if it is extraneous or not.

----------------------------

Checking x = 1

3x - 4 = sqrt(x)
3*1 - 4 = sqrt(1)
3 - 4 = 1
-1 = 1

The final equation is false, so x = 1 is not a true solution

x = 1 is extraneous.

So far, John is correct; however, we need to see the nature of the possible solution x = 16/9

So let's check it
----------------------------

Checking x = 16/9

3x - 4 = sqrt(x)
3*(16/9) - 4 = sqrt(16/9)
48/9 - 4 = 4/3
16/3 - 4 = 4/3
16/3 - 12/3 = 4/3
(16 - 12)/3 = 4/3
4/3 = 4/3

The last equation is true, so x = 16/9 is a proper solution.

This solution is considered non-extraneous. So Tim is also correct
----------------------------

They are both correct because there are two possible solutions. One of which is extraneous (x = 1) and the other is non-extraneous (the fraction x = 16/9)