Question

From the equations of the two regression lines,4x+3y+7=0 and 3x+4y+8=0,find :

Answer 1

Hello,

The two equations are

$4x + 3y = ( - 7)......(1) \times 3 \\ 3x + 4y = ( - 8)......(2) \times 4$
By elimination method



Equation becomes
$12x + 9y = ( - 21) \\ 12x + 16y = ( - 32)$

By subtracting the two
$12x + 16y = ( - 32) \\ 12x + 9y = ( - 21) \\ - \: \: \: \: - \: \: \: \: \: + \\ = = = = = = = = = = = = \\ 7y = ( - 11) \\ y = \frac{ - 11}{7}$
Putting value in equation 1 to get y
$4x + 3y = - 7 \\ 3y = - 7 - 4x \\ 3y = - 7 - 4 \times \frac{( - 11)}{7} \\ 3y = - 7 + \frac{44}{7} \\ 3y = \frac{ - 5}{7} \\ \\ y = \frac{ - 5}{21}$


Hope this will be helping you ✌️