document.write( "Question 1133871: y varies inversely with x. if y=-6 when x=-2 find y when x=5 \n" ); document.write( "
Algebra.Com's Answer #751123 by Theo(13342)![]() ![]() You can put this solution on YOUR website! the formula for inverse variation is y = k/x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for k and you get k = xy.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k is the constant of variation.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "it always remains the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "what this means is, if you multiply x by some factor, you need to divide y by the same factor.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "for example, let x = 4 and y = 8\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the constant of variation is 4 * 8 = 32\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you multiply 4 by 2, then you have to divide 8 by 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you will get 8 * 4 = 32.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k has to stay the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that is what is meant by the constant of variation.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the formula for direct variation is y = k * x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for k to get k = y / x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you multiply y by some factor, you also have to multiply x by the same factor in order to keep k the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "for example, let x = 4 and y = 8.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y / x = 2 = k\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you multiply y by 2, you have to multiply x by 2 as well in order to keep k constant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you will get 16 / 8 = 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the same concept applies whether or not the values involved are positive or minus.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "for example:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when x = -2, y = -6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k = -2 * -6 = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's your constant of variation.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if x doubles, then y must be cut in half.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "so when x becomes -4, y must becomes -3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k = xy becomes -4 * -4 = 12.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k is constant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "what happens when x becomes 4.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4 * y = 12 in order to keep k constant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for y to get y = 3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when x = -2, y = -6 \n" ); document.write( "when x = -4, y = -3 \n" ); document.write( "when x = 4, y = 3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the constant of variation was always 12. \n" ); document.write( "x * y = k \n" ); document.write( "if x is multiplied by a factor, y must be divided by the same factor in order to keep k constant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this can be seen graphically below.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your problem states:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if y = -6 when x = -2, find y when x = 5.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the formula is the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = k / x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for k to get k = y * x.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when y = -6 and x = -2, you get k = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "what happens when x = 5?\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x * y = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "when x = 5, the formula becomes 5 * y = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for y to get y = 12/5 = 2.4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-2 * -6 = 12 \n" ); document.write( "5 * 2.4 = 12\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the constant of variation is always k.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you multiplied -2 by -2.5 to get 5. \n" ); document.write( "you divided -6 by -2.5 to get 2.4.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "inverse variation says that whatever you multiply x1 by to get x2, you need to divide y1 by to get y2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in your problem, x1 was -2 and y1 was -6 while x2 was 5 and y2 was 2.4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you multiplied x1 by -2.5 to get x2 (-2 * -2.5 = 5) \n" ); document.write( "you divided y1 by -2.5 to get y2 (-6 / -2.5 = 2.4)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this can be seen graphically below.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |