# Are the equation y = 3x + 7 and y = -3x + 7 parallel?

##### 2 Answers

Sep 14, 2015

One is slope and the other way find the determinant of the matrix which should be zero for parallel lines

Write slope and intercept in matrix form

First row = (C11 C12) = (3 7)

Second row = (C 21 C22) = (-3 7)

Calculation of determinant for 2X2 matrix = C11*C22 -(-C12*C21)

i.e. (3*7- (-3*7) = 42 whic is not equal to zero

3 7

Hence these lines are not parallel