SOLUTION: GOOD EVENING....Kindly explain why y to the 7 times (-y) to the 6 =y to the 13. Is it not -y to the 13? Thank you

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Question 1004358: GOOD EVENING....Kindly explain why y to the 7 times (-y) to the 6 =y to the 13. Is it not -y to the 13? Thank you
Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
It boils down to the fact that [ minus ] x [ minus ] = [ plus ]
If you look at +%28-y+%29%5E6+, you have:
( -y ) x ( -y ) x ( -y ) x (-y ) x ( -y ) x ( -y )
Now group in groups of 2
[( -y ) x ( -y )] x [( -y ) x (-y )] x [( -y ) x ( -y )]
Now you have:
+y%5E2+%2A+y%5E2+%2A+y%5E2+=+y%5E6+
and
+y%5E7%2Ay%5E6+=+y%5E13+
---------------------
If you had +%28-y%29%5E5+, then
[( -y ) x ( -y )] x [( -y ) x (-y )] x (-y) =
+y%5E2+%2A+y%5E2+%2A%28+-y+%29+=+-y%5E5+
and
+y%5E7%2A%28-y%5E5+%29+=+-y%5E12+
Hope this helps

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
GOOD EVENING....Kindly explain why y to the 7 times (-y) to the 6 =y to the 13. Is it not -y to the 13? Thank you
y%5E7y%5E6
y%5E7 = y * y * y * y * y * y * y
%28-+y%29%5E6 = - y * - y * - y * - y * - y * - y, or y%5E6 (A negative to an EVEN exponent results in a positive)
Therefore, y%5E7y%5E6 = y * y * y * y * y * y * y * - y * - y * - y * - y * - y * - y = y%5E13, since there are 13 Ys
Much more simple than that, one of the laws of exponents states that when multiplying expressions with the same base, you simply add their exponents.
As y%5E7 and y%5E6 have the same base, (y), then y%5E7y%5E6 becomes: y%5E%287+%2B+6%29, or y%5E13