krisperry Posted October 4, 2011 Share Posted October 4, 2011 Problem 2.3.3. When x = 2 and y = -2, what is the value of x to the power of x+y plus y to the power of x-y. Ok, so here is what I (and my daughter) did at first. I substituted in the numbers: 2 to the (2+(-2)) power PLUS -2 to the (2-(-2)) power = 2 to the 0 power PLUS -2 to the fourth = 1 + (-16) = -15 We were wrong because in line 2, we should have had: 2 to the 0 power PLUS (-2) to the fourth = 1 + 16 = 17 Ok.... so I see the issue. The negative was squared as well making the answer 16 rather than -16. So here is why I was wrong: In the equation above the y was raised to the power of x+y. That is, whatever y is be it negative or positive was ALL raised to the power of x+y. When you then substitute in a negative number, you must put in the parenthesis to show that the entire number is raised. Correct? This would be far less confusing if I could actually do exponents on this forum but I can't see how to. If you have your book... it would probably be easier to flip to page 76 and read the problem for yourself. Thank you! Quote Link to comment Share on other sites More sharing options...

Cosmos Posted October 4, 2011 Share Posted October 4, 2011 The usual way to do exponents in plain text is with the caret symbol ^. Problem 2.3.3. When x = 2 and y = -2, what is the value of x to the power of x+y plus y to the power of x-y. x^(x+y) + y^(x-y) 2^(2-2) + (-2)^(2+2) 2^0 + (-2)^4 1 + 16 17 Ok.... so I see the issue. The negative was squared as well making the answer 16 rather than -16. So here is why I was wrong: In the equation above the y was raised to the power of x+y. That is, whatever y is be it negative or positive was ALL raised to the power of x+y. When you then substitute in a negative number, you must put in the parenthesis to show that the entire number is raised. Correct? Correct. Quote Link to comment Share on other sites More sharing options...

krisperry Posted October 4, 2011 Author Share Posted October 4, 2011 Oh my! I do remember the carat now. Goodness, :o Thank you! Quote Link to comment Share on other sites More sharing options...

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