help with more PS questions

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by 800GMAT » Sun May 20, 2007 3:47 pm
1. 4c2 * 3c2 = 18
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2. 6*2 + 7*4 + 8*7 + 9*9 + 10*3
...............................25
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3. 2x + x rt2 = 16 + 16 rt2
x rt2(rt2 + 1) = 16 (1 + rt2)
x rt2 = 16
x= 8 rt2
hypotenuse = x rt2 = 8 rt2 * rt2 = 16