iheartmath Posted January 18, 2011 Report Share Posted January 18, 2011 So I've had a week off from school because of the snow and I finally have to take my IB math midterm tomorrow. I found a few problems in my book that I need someone to explain to me. Your help is appreciated!!!1. Find the exact value of x for which 4^x * 5^(4x+3) = 10^(2x+3)2. Solve by completing the square: 4x^2 + 4x = 5 Reply Link to post Share on other sites More sharing options...
dessskris Posted January 18, 2011 Report Share Posted January 18, 2011 I don't have time to write and scan my working so can I just type here? Btw I answered your previous questions, did you read my answer?Qn1)4x * 54x+3 = 102x+322x * 54x * 53 = 22x * 23 * 52x * 5322x * 54x * 53 = 22x * 23 * 52x * 5352x = 2352x = 82x = log5 (8)x = log5 (8) / 2Calculate by yourself!Qn2)4x2 + 4x = 50 = 4x2 + 4x - 50 = 4 * (x2 + x - 5/4)0 = 4 * (x2 + x + (1/2)2 - 5/4 - (1/2)2)0 = 4 * [ (x + 1/2)2 - 6/4 ]0 = 4(x + 1/2)2 - 6DONE!Please check my working btw.. I just woke up and am still sleepy so idk if my Math is correctGood luck! 2 Reply Link to post Share on other sites More sharing options...
iheartmath Posted January 19, 2011 Author Report Share Posted January 19, 2011 if you find the time could you please show how to do this problem too...( (6^n + 12^n) / (1 + 2^n) ) Reply Link to post Share on other sites More sharing options...
dessskris Posted January 19, 2011 Report Share Posted January 19, 2011 Sure, sorry I was at school when you posted that so I think I am too late to reply now (6n + 12n) / (1 + 2n)= (2n*3n + 22n*3n) / (1 + 2n)= (2n*3n (1 + 2n)) / (1 + 2n)= 2n*3n= 6n Reply Link to post Share on other sites More sharing options...
heyit'salison Posted April 26, 2011 Report Share Posted April 26, 2011 Sure, sorry I was at school when you posted that so I think I am too late to reply now (6n + 12n) / (1 + 2n)= (2n*3n + 22n*3n) / (1 + 2n)= (2n*3n (1 + 2n)) / (1 + 2n)= 2n*3n= 6nI'm pretty sure 2n*3n = 62n because you add the powersSo my solution was:(6n + 12n) / (1 + 2n)= [2n x 3 + 2n x 6] / ( 1 + 2n)= [2n ( 6 + 3 )]/ (1 + 2n)= [2n (9)]/ (1 + 2n)= 9 / 1= 9 Reply Link to post Share on other sites More sharing options...
dessskris Posted April 26, 2011 Report Share Posted April 26, 2011 I'm pretty sure 2n*3n = 62n because you add the powersNo?For example 24*34=6424=1634=8116*81=129664=129668=1679616 You don't add the powers. You add power in this case:2m*2n=2m+n Reply Link to post Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.