Question

20. Solve the following pair of linear equations by cross-multiplication method:
4x + 3y = 28: 9x - 5y = 63​

Answer 1

Step-by-step explanation:

hey mate your answer is

plz mark the brilliant answer.

Answer 2

$\textrm x=7,\textrm y=0$

Step-by-step explanation:

Given  the pair of linear equation can be written as

4x+3y-28=0

9x-5y-63=0

these two equations are of the form ax+by+c=0

Here  $\textrm {a}_{1}=4, \textrm {b}_{1}=3, \textrm{c}_{1}=-28$

and $\textrm{a}_{2}=9, \textrm{b}_{2}=-5,\textrm{c}_{2}=-63$

We know from Cross multiplication,

$\textrm {x}= \dfrac{\textrm b_{1}\textrm c_{2}-\textrm b_{2}\textrm c_{1}}{\textrm a_{1}\textrm b_{2}-\textrm a_{2}\textrm b_{1}}$

and  $\textrm {y}= \dfrac{\textrm c_{1}\textrm a_{2}-\textrm c_{2}\textrm a_{1}}{\textrm a_{1}\textrm b_{2}-\textrm a_{2}\textrm b_{1}}$

$\textrm {x}= \dfrac{(3\times(-63)) -((-5)\times(-28))}{(4\times(-5))-(9\times3)}$

$\Rightarrow \textrm {x}= \dfrac{-189 -140}{-20-27}$

$\Rightarrow \textrm {x}= \dfrac{-329}{-47}$

$\Rightarrow \textrm x= 7$

now $\textrm {y}= \dfrac{((-28)\times9)-((-63)\times4)}{(4\times(-5))-(9\times3)}$

$\Rightarrow \textrm {y}= \dfrac{-252+252}{-20-27}$

$\Rightarrow \textrm y=0$