solve i know its 4 but how
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Originally Posted by perash solve i know its 4 but how You'd suspect a perfect square solution so you'd try trial and error ..... try x = 1, 4, 9 ..... whoops go back a second x = 4 aha! Alternatively: Let . Then: . Therefore: . has no real solution.
Originally Posted by mr fantastic You'd suspect a perfect square solution so you'd try trial and error ..... try x = 1, 4, 9 ..... whoops go back a second x = 4 aha! Alternatively: Let . Then: . Therefore: . has no real solution. thank you mr fantastic but if then not
Hi, Is x an integer ? I can try to make it but only if x is an integer. Let's factorize : 20 is 2²*5 is not an even number So is 2² -> And you can conclude ^^
Last edited by Moo; Mar 12th 2008 at 10:14 AM.
Originally Posted by perash thank you mr fantastic but if then not Whoops!
Similar to what mr fantastic has done: Let Solve for x and ignore any erroneous answers.
Originally Posted by o_O Similar to what mr fantastic has done: Mr F sadly adds: Unfortunately, , not ...... Let Solve for x and ignore any erroneous answers. Unfortunately that doesn't work either! But thanks for making me look less of a bonehead than I was!
Let . Then for all . Hence f is a strictly increasing function for all positive x; therefore it cannot cross the x-axis more than once. Since you have found a solution , you can be sure there can’t be any more.
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