Question

If x = -1, y = 2 is a solution of the equation 3x + 4y = k, find the value of k

Answer 1

Answer:

k = 5

Step-by-step explanation:

Given,

• x = -1
• y = 2

To find,

• The value of k

Finding k :

$\: \: \: \: \: 3x + 4y = k$

$\: \: \: \: \: : \implies \: 3 \times ( - 1) + 4 \times 2 = k$

$\: \: \: \: \: : \implies \: - 3 \: + \: 8 = k$

$\: \: \: \: \: : \implies \: 5 = k$

Checkout :

$\: \: \: \: \: 3x + 4y = k$

$\: \: \: \: \: : \implies \: 3 \times ( - 1) + 4 \times 2 = 5$

$\: \: \: \: \: : \implies - 3 \: + 8 = 5$

$\: \: \: \: \: : \implies \: 5 \: = \: 5$

$\: \: \: \: \: \therefore \: LHS \: = RHS$

$\underline{\fbox{\blue{\rm{Hence, \: k=5 \: is \: the \: correct\: answer. }}}}$

Answer 2

Given :-

• x = -1
• y = 2

To find :-

• The value of k

Finding k :

$\: \: \: \: \: 3x + 4y = k$

$:➝~3 \times ( - 1) + 4 \times 2 = k$

$:➝~- 3 + 8 = k$

$:➝~5 = k$

Checkout :-

$\: \: \: \: \: 3x + 4y = k$

$:➝~3 \times ( -1) + 4 \times 2 = 5$

$:➝~- 3 + 8 = 5$

$:➝~5 = 5$

${\sf{~~~~~~~.°. LHS = RHS}}$

Hence,

${ \underline{ \boxed{ \odot\mid{ \sf{k=5~is~the~correct~answer}}}}}$$\large{\bf\green{✓}}$