Problem
Each member of a research group visited either the Virgin Islands or Hawaii...
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So What?
Math questions involving two equations and two unknowns can usually be combined into one equation with one unknown.
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ACT: Math Question #1 |
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Question:
| If |
2 |
u |
+ |
2 |
= |
20 |
, and |
v |
- |
2 |
u |
= |
-2 |
, what is the value of |
v |
? |
Choices:
The correct answer is E.
This system of equations can be solved by substitution or combination. In this case, combination is quicker.
| To do this, add |
( |
2 |
u |
+ |
2 |
= |
20 |
) |
and |
( |
v |
- |
2 |
u |
= |
-2 |
) |
| Adding the two equations makes the |
2 |
u |
and |
-2 |
u |
cancel, and you |
| are left with |
v |
+ |
2 |
= |
18. |
Subtracting 2 from both sides gives you: |
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