It is known that x1 and x2 are roots of the equation x2−8x+k=0, where 3x1+4x2=29. Find k.

(note it is not 3x^1 and 4x^2 it is 3x sub 1 and 4x sub 2)

Respuesta :

Answer:

The answer to your question is   k = -3233

Step-by-step explanation:

Data

x₁, x₂ are the roots

Equation l      x² - 8x + k = 0

Equation ll     3x₁ + 4x₂ = 29

k = ?

Process

1.- Write another equation

                     x₁ + x₂ = - 8

2.- Solve the system of equations by elimination

                      3x₁ + 4x₂ = 29          Equation l

                        x₁ +   x₂ = -8            Equation ll

-Multiply equation ll by -3

                      3x₁  + 4x₂ = 29

                    -3x₁   - 3x₂ = 24

                       0    + x₂ = 53

-Find x₁

                       x₁ + 53 = -8

                       x₁ = -8 - 53

                       x₁ = -61

2.- Find k

                      (x₁)(x₂) = k

                      (53)(-61) = k

                      k = -3233

Answer:

K is equal to 15

Step-by-step explanation:

So first we have to find a, b, and c. (Vieta's Theorem)

a=1

b=-8

c=k

next, let us create our systems of equations. Let x1 be x and x2 be y.

x+y=8

x*y=k/1

3x+4y=29

After solving we get:

x=3

y=5

k=15