Question

solve these equations only by substitution method--- 2x-3y=13,
7x-2y=20



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Answer 1

Answer:

x = + 2

y = - 3

Step-by-step explanation:

Given equations are :

2x - 3y = 13 __(A)

7x - 2y = 20 __(B)

Now, we can write eq. (A) as

2x = 13 + 3y

x = $\dfrac{13\:+\:3y}{2}$ __(1)

Put value of x in eq. (B)

$\implies$ 7 $(\dfrac{13 \: + \: 3y}{2} )$ - 2y = 20

$\implies$ $( \dfrac{91 \: + \: 21y}{2} )$ - 2y = 20

$\implies$ $( \dfrac{91 \: + \: 21y \: - 4y}{2} )$= 20

$\implies$ $( \dfrac{91 \: + \: 17y}{2} )$ = 20

$\implies$ 91 + 17y = 20 × 2

$\implies$ 91 + 17y = 40

$\implies$ 17y = 40 - 91

$\implies$ 17y = - 51

• $\boxed{\bold{y \: = \:- 3 }}$

Put value of y in eq. (1)

$\implies$ x = $\dfrac{13\:+\:3(-3)}{2}$

$\implies$ x = $\dfrac{13\:-\:9}{2}$

$\implies$ x = $\dfrac{4}{2}$

• $\boxed{\bold{x \:=\: + 2}}$