Question

solve by formula x²-3x-4=0​

Answer 1

Answer:

x = -1,4

Step-by-step explanation:

x²-3x-4=0​

=> x²-4x+x-4=0​

=> x(x-4)+1(x-4) = 0

=> (x-4)(x+1) = 0

=> x = -1,4

Answer 2

Answer:

here

now x² - 3x = 4

Step-by-step explanation:

ANSWER

Given,

x² −3x−4=0

⇒x²−3x−4+4=4

⇒x² −3x=4

To make a trinomial square on the left side of the equation, We have to find a value that is equal to the square of half of b, the coefficient of x.

So, (

2

b

)

2

=(−

2

3

)

2

Adding the term to both sides of the equation,

x

2

−3x+(−

2

3

)

2

=4+(−

2

3

)

2

⇒x

2

−3x+

4

9

=

4

25

⇒x

2

+2⋅x⋅(−

2

3

)+(−

2

3

)

2

=

4

25

⇒(x−

2

3

)

2

=

4

25

Taking square root of both sides we get,

(x−

2

3

)

2

=±

4

25

⇒x−

2

3

=±

2

5

For

2

5

,x−

2

3

=

2

5

⇒x=

2

5

+

2

3

=4

For −

2

5

,x−

2

3

=−

2

5

⇒x=−

2

5

+

2

3

=−1

Hence, the solution is x=4,−1.