Veritas Prep GMAT Instructor
Joined: 23 Oct 2013
Posts: 143
Given Kudos: 9
Re: Functions
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29 Oct 2013, 05:05
I like how you assess the statements individually at first, and then in tandem second. That is always the right approach with data sufficiency questions.
In statement 1, you are correct. The order in which the numbers/variables are positioned does not matter for addition or multiplication, so statement 1 could imply either addition or subtraction. It cannot, however, imply subtraction or division, as the positioning of the numbers/variables here does matter.
In statement 2, it can only be addition. This is a great problem for picking numbers. With x=1, you are correct in that both multiplication and addition will yield the same result (4). However, you need to test more than one number. This operation must hold for all positive numbers, not just x=1. So let's try x=10. Addition: 2(10)+2(10) = 40 and 4(10) = 40, so this work. Now let's try multiplication: 2(10)*2(10) = 20*20 = 400 and 4(10) = 40, so multiplication does NOT work. Thus the * symbol must represent addition.
Remember to always pick multiple different kinds of numbers when employing the picking numbers strategy. Different kinds of numbers include positive/negative, odd/even, integers/fractions, large numbers, and the numbers 0 and 1.
I hope this helps!!!