RIDDLE Posted January 5, 2019 Share Posted January 5, 2019 how to do question 28-30 Link to comment Share on other sites More sharing options...
studiot Posted January 5, 2019 Share Posted January 5, 2019 2 hours ago, RIDDLE said: how to do question 28-30 1) Each of questions 28, 29 and 390 should have their own thread. 2) Have you had no thoughts about any of these to tell us? 3) Taking the average question, since it is the simplest, what would you do in elementary algebra if faced with the question Simplify [math]\frac{{a + b}}{{a - b}}[/math] Simplify means write out the expression on one line not two. Link to comment Share on other sites More sharing options...
peterwlocke Posted January 22, 2019 Share Posted January 22, 2019 b over -b ? Link to comment Share on other sites More sharing options...
druS Posted January 26, 2019 Share Posted January 26, 2019 Studiot you have me intrigued as this is basic enough math that I should be able to handle it. I dont want to blow it for the OP and actually dont know I'm right. But I start by multiplying by -1/-1 Is it the right direction? Link to comment Share on other sites More sharing options...
studiot Posted January 26, 2019 Share Posted January 26, 2019 (edited) 2 hours ago, druS said: Studiot you have me intrigued as this is basic enough math that I should be able to handle it. I dont want to blow it for the OP and actually dont know I'm right. But I start by multiplying by -1/-1 Is it the right direction? Yes, multiply by 1 (why the minus signs?) Now 1 equals [math]1 = \frac{{\left( {1 + i} \right)}}{{\left( {1 + i} \right)}}[/math] So we have [math]\frac{{\left( {1 + i} \right)}}{{\left( {1 - i} \right)}}*\frac{{\left( {1 + i} \right)}}{{\left( {1 + i} \right)}} = \frac{{\left( {1 + 2i + {i^2}} \right)}}{{{{\left( 1 \right)}^2} - {{\left( i \right)}^2}}} = \frac{{2i}}{2} = i[/math] Since the bottom then becomes the difference of two squares. I think this thread is now old enough that the OP has lost interest. Edited January 26, 2019 by studiot Link to comment Share on other sites More sharing options...
HallsofIvy Posted February 28, 2019 Share Posted February 28, 2019 28 is straight forward if you know some basic facts: The midpoint of the line segment between (x_1, y_1) and (x_2, y_2) is ((x_1+ x_2)/2, (y_1+ y_2)/2). The slope of the line between those two points is m= (y_2- y_1)/(x_2- x_1). The line perpendicular to y= mx+ b has slope -1/m. The distance between points (x_1, y_1) and (x_2, y_2) is sqrt((x_2- x_1)^2+ (y_2- y_1)^2). Whoever gave you this problem expects you to know that! Link to comment Share on other sites More sharing options...
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