Question

Find p if points( -3, 12)( 7,6)( p, 9 )are collinear

Answer 1

Answer:

2

step 1:

$1\2|x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2) | = 0$

step 2:

$1\2 | - 3(6 - 9) + 7(9 - 12) + p(12 - 6)| = 0$

step 3:

$1\2 | - 3( - 3) + 7( - 3) + p(6)|$

step 4:

$1\2 | - 12 + 6p|$

step 5:

$|6p - 12|\2 = 0$

step 6:

$3p - 6 = 0$

step 7:

$p = 6\3 = 2$