document.write( "Question 703395: What is the function for (5,19)(2,10)(-3,-5) \n" ); document.write( "
Algebra.Com's Answer #433508 by AnlytcPhil(1806)\"\" \"About 
You can put this solution on YOUR website!
 We plot the three points:\r\n" );
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document.write( "So we'll pick two of them and get the equation\r\n" );
document.write( "of the line through them, and check to see if the\r\n" );
document.write( "third point satisfies the equation.\r\n" );
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document.write( "We find the slope of the line through \r\n" );
document.write( "(5,19) (2,10) using the slope formula:\r\n" );
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document.write( "m = \"%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29\"\r\n" );
document.write( "m = \"%2810-19%29%2F%282-5%29\"\r\n" );
document.write( "m = \"%28-9%29%2F%28-3%29\"\r\n" );
document.write( "m = 3\r\n" );
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document.write( "Then we use the point-slope formula:\r\n" );
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document.write( "y - y1 = m(x - x1\r\n" );
document.write( "y - 19 = 3(x - 5)\r\n" );
document.write( "y - 19 = 3x - 15\r\n" );
document.write( "     y = 3x + 4\r\n" );
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document.write( "Now we check to make sure the third given\r\n" );
document.write( "point (-3,-5) satisfies that equation\r\n" );
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document.write( "     y = 3x + 4\r\n" );
document.write( "    -5 = 3(-3) + 4\r\n" );
document.write( "    -5 = -9 + 5\r\n" );
document.write( "    -5 = -5\r\n" );
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document.write( "It does, so y = 3x + 4 is the function.\r\n" );
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document.write( "But we write it in function notation\r\n" );
document.write( "by substituting f(x) for y:\r\n" );
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document.write( "    f(x) = 3x + 4\r\n" );
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document.write( "Edwin
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