Find the value of x and y respectively if 3x - 5y + 5 = 0 and 4x - 7y + 8 = 0

  • A -5, -4
  • B -4,. -5
  • C 4, 5
  • D 5, 4
jamb 2003mathematics

The correct answer is D. 5, 4

3x - 5y + 5 = 0 → eqn1

4x - 7y + 8 = 0 → eqn2

eqn1 4; 12x - 20y + 20 = 0 → eqn3

eqn2 3; 12x - 21y + 24 = 0 → eqn4

eqn3 - eqn4 = y - 4 = 0

∴ y = 4

From eqn1,

3x - 5y + 5 = 0

3x - 5(4) + 5 = 0

3x - 20 + 5 = 0

3x - 15 = 0

3x = 15

x = 5

x and y = 5, 4 respectively

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