Question

4 x + 3 Y = 17
3 x - 4 Y + 6= 7
PLEASE SOLVE ONLY MY CROSS MULTIPLICATION METHOD

Answer 1

Given System of equations is :

4x + 3y - 17 = 0 ------ (1)

3x - 4y + 6 - 7 = 0

3x - 4y - 1 = 0  ------ (2)

Compare the above equations with a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0,

a1 = 4, b1 = 3, c1 = -17

a2 = 3, b2 = -4, c2 = -1


Now,

$\frac{x}{b1c2 - b2c1} = \frac{-y}{a1c2- a2c1} = \frac{1}{a1b2 - a2b1}$

$= \ \textgreater \ \frac{x}{3(-1) - (-4)(-17)} = \frac{-y}{(4)(-1) - (3)(-17)} = \frac{1}{(4)(-4) - (3)(3)}$

$= \ \textgreater \ \frac{x}{-71} = \frac{-y}{47} = \frac{1}{-25}$

$= \ \textgreater \ \frac{x}{-71} = \frac{1}{-25}$

$x = \frac{71}{25}$



$= \ \textgreater \ \frac{-y}{47} = \frac{-1}{25}$

$= \ \textgreater \ y = \frac{47}{25}$




Therefore x = 71/25, y = 47/25.


Hope this helps!