Home
Class 9
MATHS
Use method of cross-multiplications to s...

Use method of cross-multiplications to solve:
` 2x + y = 8 and 3x- 2y = 5`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the system of equations using the method of cross-multiplication, we start with the given equations: 1. \( 2x + y = 8 \) 2. \( 3x - 2y = 5 \) ### Step 1: Reformat the equations We need to rewrite both equations in the standard form \( a_1x + b_1y + c_1 = 0 \) and \( a_2x + b_2y + c_2 = 0 \). Rearranging the first equation: \[ 2x + y - 8 = 0 \quad \Rightarrow \quad 2x + 1y - 8 = 0 \] Rearranging the second equation: \[ 3x - 2y - 5 = 0 \quad \Rightarrow \quad 3x - 2y - 5 = 0 \] Now we have: - \( a_1 = 2, b_1 = 1, c_1 = 8 \) - \( a_2 = 3, b_2 = -2, c_2 = 5 \) ### Step 2: Apply the cross-multiplication formulas Using the cross-multiplication method, we can find \( x \) and \( y \) using the formulas: \[ x = \frac{b_1c_2 - c_1b_2}{a_1b_2 - b_1a_2} \] \[ y = \frac{c_1a_2 - c_2a_1}{a_1b_2 - b_1a_2} \] ### Step 3: Calculate \( x \) Substituting the values into the formula for \( x \): \[ x = \frac{(1)(5) - (8)(-2)}{(2)(-2) - (1)(3)} \] Calculating the numerator: \[ 1 \cdot 5 = 5 \] \[ 8 \cdot -2 = -16 \quad \Rightarrow \quad -(-16) = 16 \] So, the numerator becomes: \[ 5 + 16 = 21 \] Calculating the denominator: \[ (2)(-2) = -4 \] \[ (1)(3) = 3 \] So, the denominator becomes: \[ -4 - 3 = -7 \] Now substituting back: \[ x = \frac{21}{-7} = -3 \] ### Step 4: Calculate \( y \) Substituting the values into the formula for \( y \): \[ y = \frac{(8)(3) - (5)(2)}{(2)(-2) - (1)(3)} \] Calculating the numerator: \[ 8 \cdot 3 = 24 \] \[ 5 \cdot 2 = 10 \] So, the numerator becomes: \[ 24 - 10 = 14 \] Using the same denominator as before: \[ -4 - 3 = -7 \] Now substituting back: \[ y = \frac{14}{-7} = -2 \] ### Final Solution Thus, the solution to the system of equations is: \[ x = 3, \quad y = 2 \]
Promotional Banner

Topper's Solved these Questions

  • CHAPTERWISE REVISION (STAGE 1)

    ICSE|Exercise Indices|14 Videos
  • CHAPTERWISE REVISION (STAGE 1)

    ICSE|Exercise logrithms|20 Videos
  • CHAPTERWISE REVISION (STAGE 1)

    ICSE|Exercise Factorisation |26 Videos
  • CHAPTER REVISION (STAGE 2)

    ICSE|Exercise DISTANCE FORMULA |12 Videos
  • CHAPTERWISE REVISION (STAGE 3)

    ICSE|Exercise DISTANCE FORMULA |11 Videos

Similar Questions

Explore conceptually related problems

Use method of cross-multiplications to solve: x+ 4y = 3 and 2x + 9 y = 5

Solve 3x - 4y = 20 and x + 2y = 5.

Solve by cross - multiplication : 2x + 3y = 6 and 6x - 5y = 4 .

Solve the following system of equations by using the method of cross-multiplication: 2x+3y=17 ,\ \ \ \ 3x-2y=6

Solve the following system of equations by using the method of cross multiplication 2x + 3y = 7 and 6x + 5y = 11.

Solve the following system of equations by method of cross-multiplication: x+a y=b ,\ \ \ \ a x-b y=c

Solve, using cross - multiplication : 2x + 3y - 17 = 0 and 3x - 2y - 6 = 0 .

Solve the following system of equations by method of cross-multiplication: a x+b y=a-b ,\ \ \ \ b x-a y=a+b

Solve by cross - multiplication : 3x + y = 13 and x - 3y + 9 = 0.

Solve the following system of equations by method of cross-multiplication: 2x+y=35 ,\ \ \ \ 3x+4y=65