document.write( "Question 946075: What is a sign graph and when is it used? Give an example. Explain what the test-point method is and how it is used to solve a quadratic inequality. Be sure to show the connection between the test-point method and a sign graph. (I am completely lost Please Help!) \n" ); document.write( "
Algebra.Com's Answer #577189 by rothauserc(4718)![]() ![]() You can put this solution on YOUR website! 1)If we can factor a quadratic inequality, then the inequality can be solved with a sign graph, which shows where each factor is positive, negative, or zero. \n" ); document.write( "for example, \n" ); document.write( "x^2 +3x -10 > 0 \n" ); document.write( "factor polynomial \n" ); document.write( "(x+5)*(x-2) > 0 \n" ); document.write( "This inequality says that the product of x + 5 and x - 2 is positive. If both factors are negative or both are positive, the product is positive. To analyze the signs of each factor, we make a sign graph. First consider the possible values of the factor x + 5 \n" ); document.write( "x+5=0 if x=-5 put 0 above -5 on number line \n" ); document.write( "x+5>0 if x>-5 put + to the right of -5 \n" ); document.write( "x+5<0 if x<-5 put - to the left of -5 \n" ); document.write( "now do the same analysis for x-2=0, x-2>0, x-2<0 \n" ); document.write( "2) First determine zeros for the polynomial in 1 \n" ); document.write( "(x+5)*(x-2) = 0 and \n" ); document.write( "zeros are -5 and 2 \n" ); document.write( "To solve by the Test-Point Method, pick a sample point in each interval, the intervals being (negative infinity, –5), (-5, 2), (2, positive infinity) \n" ); document.write( "remember that our inequality from 1 is \n" ); document.write( "x^2 +3x -10 > 0 \n" ); document.write( "evaluate the inequality for each test point and \n" ); document.write( "(note that we are interested in the interval/s that give us a positive value) \n" ); document.write( "If the rational expression is greater than 0, then we are interested in values that cause our rational expression to be positive. \n" ); document.write( "3) both methods use the sign of evaluated expressions to find the solution set. \n" ); document.write( " |