2z^2+7z-15=0

What is the solution set for the equation?

a. {5,-3/2}
b. {-5,3/2}
c. {-5, 3}
d. {5,-3}

Question

2z^2+7z-15=0

What is the solution set for the equation?

a. {5,-3/2}
b. {-5,3/2}
c. {-5, 3}
d. {5,-3}

anonymous · Answer

Two ways to solve this:

a) Solve the equation and look for a pair that contains both of those
b) Try to plug in each solution from each set and choose the solution set whose all solutions really solve the equation

anonymous · Answer

Clarification for step b: if you plug in e.g. z=5 and find out that the equation holds, you know the answer is either a or d. If it doesn't hold, it is either b or c.

Doing similar reasoning for other values enables you to quickly rule out incorrect alternatives.

anonymous · Answer

Okay. Thanks for clearing that up.

anonymous · Answer

Since these look like school problems, see if it can be factored first.  This one factors as follows: (z + 5) (2 z - 3)