Question

Giselle solved the quadratic equation x^2+5x-6=0 by factoring. Her work shown below. In which step did she first make a mistake? Find the correct answer. Step 1: x^2+5x-6=0 Step 2: (x+2)(x+3)=0 Step 3: x+2=0, x+3=0 Step 4: x=-2 or x=-3 Step 5: {-2,-3}

Answer 1

x = - 6 or, 1

Explanation:

The given quadratic equation:

`x^2+5x-6=0`

By factorisation mmethod,

`x^2+6x-x-6=0`

⇒ x(x + 6) - 1(x + 6) = 0

⇒ (x + 6)(x - 1) = 0

⇒ x + 6 = 0 or, x - 1 = 0

⇒ x + 6 = 0 ⇒ x = - 6

⇒ x - 1 = 0 ⇒ x = 1

∴ x = - 6 or, 1