document.write( "Question 646777: If the line passing through the points (1, a) and (4, -2) is parallel to the line passing through the points (2, 8) and (-7, a + 4), what is the value of a?\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Thanks for your help. \n" ); document.write( "

Algebra.Com's Answer #405936 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

 
\n" );
document.write( "Hi,
\n" );
document.write( "parellel lines have identical slopes
\n" );
document.write( "(1, a) and 
\n" );
document.write( "(4, -2) \r
\n" );
document.write( "\n" );
document.write( "(2, 8) and 
\n" );
document.write( "(-7, a + 4)  \r
\n" );
document.write( "\n" );
document.write( " |Multiplying thru by 9 so as all denominators = 1
\n" );
document.write( "-3(a+2) = 8-(a+4)
\n" );
document.write( " -3a - 6 = 8 -a - 4
\n" );
document.write( "    -10 = 2a
\n" );
document.write( "    -5 = a
\n" );
document.write( "and...
\n" );
document.write( "(1, -5) and 
\n" );
document.write( "(4, -2) m = -3/-3 = 1
\n" );
document.write( "(2, 8) and 
\n" );
document.write( "(-7, -1) m = 9/9 = 1 \n" );
document.write( "

\n" );