Question

Solve the linear equation : i) 4 + 5 =7 ; 3 + 4 =5​

Answer 1

4x + 5y = 7

3x + 4y = 5

Solution :

• We Can Solve It By Four Methods Of Linear Equation
• (1) Graphical Method
• (2) Substitute Method
• (3) Elimination Method
• (4) Multiplication Method

Now, I want to apply here substitute method

(Note :- you Can apply any of these methods)

Now, First of All We should make x value w.r.t y

4x + 5y = 7 ____(1)

3x + 4y = 5 ____(2)

Hence,

we picked eq (1) for x value

4x + 5y = 7 ____(1)

4x = 7 - 5y

x = $\sf \frac{7 - 5y}{4} ...(3)$

Now, put the value of eq (3) in eq (2)

3x + 4y = 5 ____(2)

• $\sf 3 \bigg(\frac{7 - 5y}{4} \bigg) + 4 y = 5$

• $\sf \frac{21 - 15y}{4} + 4y = 5$

• $\sf \frac{21 - 15 y + 16 y }{4 }= 5$

• $\sf 21- y = 4 × 5$

• $\sf 21 - y = 20$

• $\sf 21 - 20 = y$

• $\sf 1 = y$

• $\sf \underline{\underline{ \red{ y = 1}}}$

Now, put the value of y in eq (3)

• x = $\sf \frac{7 - 5y}{4} ...(3)$

• x = $\sf \frac{7 - 5(1)}{4}$

• x = $\sf \frac{7 - 5}{4}$

• x = $\sf \frac{2}{4}$

• x = $\sf \frac{\cancel 2^{\: \: 1}}{\cancel 4_{\: \: 2}}$

• $\sf \underline{\underline{\red{x = \frac{1}{2}}}}$

Hence , ( x , y ) = ( 1/2 , 1 )

I hope it helps you ❤️✔️