Question

J={x:x€ R and x squared +x -12=0}​

Answer 1

QUESTION :-

J = { x : x € R where x^2 + x - 12 = 0}

SOLUTION :-

We know that x belongs to Real numbers and we use FACTORIZATION to find the value of x

x^2 + x - 12 = 0

x^2 + 4x - 3x - 12 = 0

x(x + 4) - 3 (x + 4) = 0

(x - 3)(x + 4) = 0

x - 3 = 0

x = 3

and

x + 4 = 0

x = -4

Here the values of x are 3 and -4

So,

J = {-4 , 3}

Answer 2

x² + x - 12 = 0

⇒ x² - 3x + 4x - 12 = 0

⇒ x(x - 3) + 4(x - 3) = 0

⇒ (x+4) (x-3) = 0

case 1 :

x+4 = 0

⇒ x = -4

case 2 :

x - 3 = 0

⇒ x = 3

∴ x = { -4 , 3 }

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