Question

by elimination method { chapter simultaneous linear equations class 9 ICSE)
2x+3y = 23

5x-20 = 8y​

Answer 1

$\huge\boxed{\mathtt\red{Solution:-}}$

$\large\boxed{\mathtt\blue{Given:-}}$

• 2x+3y = 23
• 5x-20 = 8y

$\large\boxed{\mathtt\green{Solving:-}}$

⟹ 2x+3y = 23

⟹ 5x-20 = 8y ⟹ 5x-8y = 20

Now,

Multiplying both the equation by 5 and 2 respectively :-

⟹ 5(2x+3y) = 5×23

✒ 10x+15y = 115 ...(i)

⟹ 2(5x-8y) = 2×20

✒ 10x-16y = 40 ...(ii)

Now, subtract ...(i) from (ii)

10x+15y = 115

-10x+16y = -40

---------------------------------

31y = 75

∴ y = 75/31

✒ x = (115-15y)/10

putting the value :-

✒ x = {115-(15×75/31)}/10

∴ x = 244/31