document.write( "Question 1128653: Hi can you plz help me with this qs? I didn't know under which section to post it so im posting it here:
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document.write( "the curve y = ax^3 + bx^2 + cx + d has a gradient of -3 at (0, 15/2) and a turning point at (3,6). Find a,b,c,d
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Algebra.Com's Answer #745144 by greenestamps(13200)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "y = ax^3+bx^2+cx+d \n" ); document.write( "y' = 3ax^2+2bx+c \n" ); document.write( "y'' = 6ax+2b \n" ); document.write( "The given information tells us... \n" ); document.write( "y(0) = 15/2 --> c = 15/2 (1) \n" ); document.write( "y(3) = 6 --> 27a+9b+3c+d = 6 (2) \n" ); document.write( "y'(0) = -3 --> c = -3 (3) \n" ); document.write( "y''(3) = 0 --> 18a+2b = 0 (4) \n" ); document.write( "Substitute (1) and (3) in (2): \n" ); document.write( "27a+9b-9+15/2 = 6 \n" ); document.write( "27a+9b = 15/2 \n" ); document.write( "18a+6b = 5 (5) \n" ); document.write( "Subtract (4) from (5): \n" ); document.write( "4b = 5 \n" ); document.write( "b = 5/4 (6) \n" ); document.write( "Substitute (6) in (4): \n" ); document.write( "18a+5/2 = 0 \n" ); document.write( "a = -5/36 \n" ); document.write( "The polynomial is \n" ); document.write( " \n" ); document.write( "A graph... \n" ); document.write( " |