How do you check that the solution to #2(5 - 2z) = 20 - 2(z - 1)# is -5?

Answer 1

Kennedy Adams

To check if -5 is a solution to the equation 2(5 - 2z) = 20 - 2(z - 1):

Substitute -5 for z in the equation.
Simplify both sides of the equation.
If both sides are equal, then -5 is a solution.

Let's do the calculation: 2(5 - 2(-5)) = 20 - 2((-5) - 1) 2(5 + 10) = 20 - 2(-6) 2(15) = 20 + 12 30 = 32

Since 30 is not equal to 32, -5 is not a solution to the equation.

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Answer 2

Julia Adams

I'm afraid it's not. Expanding: #2(5−2z)=10-4z# and #20−2(z−1) = 20-2z+2# Now we can bring all the variables on the left, and all the numbers to the right: #-2z=20-10+2# which yelds #-2z=12# and thus #z=-6#

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.