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Zorluk: KolaySystems of Linear Equations

If x+y=8x + y = 8 and 2xy=72x - y = 7, what is the value of xx?

  1. 5Cevap
  2. B
    3
  3. C
    1
  4. D
    15
  5. E
    11

Cevap

5
Adding the two equations yields (x+y)+(2xy)=8+7(x + y) + (2x - y) = 8 + 7, which simplifies to 3x=153x = 15. Dividing both sides by 3 gives the correct value, x=5x = 5.

Adım Adım Çözüm

1
Add the two equations together to eliminate the variable yy.
(x+y)+(2xy)=8+7    3x=15(x + y) + (2x - y) = 8 + 7 \implies 3x = 15
Since the coefficients of yy are +1+1 and 1-1, adding the equations eliminates yy directly.
2
Solve for xx by dividing both sides of the equation by 3.
x=153=5x = \frac{15}{3} = 5
Isolating xx gives the required solution.

Anahtar Kavram

Elimination Method in Systems of Linear Equations
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