Question

Find the sum of x2 + 3x and -2x2 + 9x +5.​

Answer 1

This is the answer

Explanation:

Solving 3x2-9x-5 = 0 by the Quadratic Formula .

According to the Quadratic Formula, x , the solution for Ax2+Bx+C = 0 , where A, B and C are numbers, often called coefficients, is given by :

- B ± √ B2-4AC

x = ————————

2A

In our case, A = 3

B = -9

C = -5

Accordingly, B2 - 4AC =

81 - (-60) =

141

Applying the quadratic formula :

9 ± √ 141

x = —————

6

√ 141 , rounded to 4 decimal digits, is 11.8743

So now we are looking at:

x = ( 9 ± 11.874 ) / 6

Two real solutions:

x =(9+√141)/6=3/2+1/6√ 141 = 3.479

or:

x =(9-√141)/6=3/2-1/6√ 141 = -0.479

Two solutions were found :

x =(9-√141)/6=3/2-1/6√ 141 = -0.479

x =(9+√141)/6=3/2+1/6√ 141 = 3.479