Question

solve the pair of linear equation 3x+4y=12 and 4y+7x=12 by the method of cross multiplication​

Answer 1

Step-by-step explanation:

given equations are 3x+4y=12=》3x+4y-12=0

4x+7y=12=》4x+7y-12=0

by cross multiplication x y 1

4 -12 3 4

7 -12 4 7

=》x/-48+84 =y/-48+36 =1/21-16

=》x/36=y/-12 =1/5

=》x=36/5;y= -12/5

Answer 2

Answer: x=-36/5,y=-12/5

Step-by-step explanation:

Given,

3x+4y=12  equation 1

4y+7x=12  equation 2

To do cross multiplication use the formula

$\frac{x}{(b1c2-b2c1)} =\frac{y}{(c1a2-a1c2)} =\frac{-1}{(a1b2-a2b1)}$

$\frac{x}{(4*12-7*12)} =\frac{y}{(12*4-3*12)} =\frac{-1}{(3*7-4*4)}$

$\frac{x}{(48-84)} =$$\frac{y}{(48-36)} =\frac{-1}{(21-16)}$

$\frac{x}{-36}=\frac{y}{12} =\frac{-1}{5}$

x=-36/5

y=-12/5

Therefore, x=-36/5,y=-12/5