Question

Find the solutions of x^2 + x - 12 = 0

Answer 1

Step-by-step explanation:

x^2+ x-12=0

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

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

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

x=3, -4

Answer 2

Step-by-step explanation:

We can Split the Middle Term of this expression to factorise it and thereby find solutions.

In this technique, if we have to factorise an expression like

ax2+bx+c

, we need to think of 2 numbers such that:

N1⋅N2=a⋅c=1⋅−12=−12 AND

N1+N2=b=−1

After trying out a few numbers we get

N

1

=

3

and

N

2

=

−

4

3

⋅

−

4

=

−

12

, and

3

+

(

−

4

)

=

−

1

x

2

−

x

−

12

=

x

2

−

4

x

+

3

x

−

12

x

(

x

−

4

)

+

3

(

x

−

4

)

=

0

(

x

+

3

)

(

x

−

4

)

=

0

Now we equate the factors to zero.

x

+

3

=

0

,

x

=

−

3

x

−

4

=

0

,

x

=

4