Question

15x + 17y= 31 and 17x±15x= 21 find the value of [x,y]. ​

Answer 1

$\sf \: 15x \: + \: 17y \: = \: 31 \\ \\ \sf \: 15x \: = \: 31 - 17y \\ \\ \sf \: x \: = \: \frac{31 \: - \: 17y}{15}$

${ \underline{\sf \: Putting \: the \: value \: of \: x \: in \: 15x \: + \: 17y \: = \: 31}}$

$\sf \: \cancel{15 }\: \times \frac{31 \: - \: 17y}{ \cancel{15}} \: + \: 17y \: = \: 31$

$\sf \: 31 \: - \: \: 17y \: + \: 17y \: = \: 31$

$\sf31 \: + y \: = \: 31$

$\sf \: y \: = \: 31 - 31 \\ \\ \sf y \: = \: 0$

Putting the value of y in the given equation, we get,

$\sf15x \: + \: 17 \: \times \: 0 \: = \: 31 \\ \\ \sf \: 15x \: + \: 0 \: = \: 31 \\ \\ \sf \: x = \sf\frac{31}{15} \\ \\ \sf \: x \: = \: 2.0666 \: (approx)$

$\sf \therefore\:x\:=\:2.0666\:(approx)\:and\:y\:=\:0$

$\color{lime}\rule{200000000 pt}{2pt}$

Answer 2

Step-by-step explanation:

15x+17y=31----(i)

17x+15x=21----(ii)

=>32x=21

=>x=21/32

17x-15x=21-----(iii)

=>2x=21

=>x=21/2

(i)---

15×(21/32)+17y=31

y=677/544

or,

15×(21/2)+17y=31

y= -253/34

[x,y]= [21/32, 677/544] or [21/2, -253/34]