Question

solve:4x+3y=30,5x+4y=39​

Answer 1

$\mathfrak{\large{\underline{\underline{Answer:-}}}}$

$\boxed{\sf{x = 3, \: y = 6}}$

$\mathfrak{\large{\underline{\underline{Explanation:-}}}}$

Given :- 4x + 3y = 30

5x + 4y = 39

To find : Value of x and y

Solution :-

4x + 3y = 30 -----(1)

5x + 4y = 30 ----(2)

Now multiply (1) by 5

$4x(5) + 3y(5) = 30(5)$

$20x + 15y = 150 - - - - - (3)$

Multiply (2) by 4

$5x(4) + 4y(4) = 39(4)$

$20x + 16x = 156 - - - - - - (4)$

Subtract (3) from (4)

20x + 16x = 156

20x + 15y = 150

(-)***(-)****(-)

__________________

y = 6

___________________

Substitute y = 6 in (1)

$4x + 3(6) =30$

$4x + 18 = 30$

$4x = 30 - 18$

$4x = 12$

$x = \dfrac{12}{4}$

$x = 3$

$\Huge{\boxed{\sf{x = 3, \: y = 6}}}$

$\mathfrak{\large{\underline{\underline{Verification:-}}}}$

Let us check with eq(1) first.

$4(3) + 3(6) = 30$

$12 + 18 = 30$

$30 = 30$

Now check with (3)

$5(3) + 4(6) = 39$

$15 + 24 = 39$

$39 = 39$

$\mathfrak{\underline{\underline{Note:-}}}$

The method that is used to solve the question is Elimination method .

Answer 2

ANSWER:

given equations are

4x+3y=30

multiply the equation with 5

then

20x+15y=150--------------------(1)

and the next equation is

5x+4y=39

multiply this equation with 4

then

20x+16y=156---------------(2)

(2)-(1)

20x+16y=156

(-)20x-15y=-150

_________________

y=6

_________________

$\Huge \sf {\boxed {y = 6}}$

substitute y value in

equation given

4x+3y=30

4x+18=30

4x=12

$\Huge \sf {\boxed{ x = 3}}$

ALTERNATIVE:

so the method I have done to find the values of x and y is elimination method

u can also do this or solve this by

substitution method

in that

from the first equation

we need to write x in the terms of y and substitute in the other equation.