Question

X = ✓5+1/2 , find value of 2x^3 +x^2 -5x+4​

Answer 1

Answer:

Let f(x)=x2−5x+4

substituting  x = 3.

f(x)=32−5(3)+4

= 9 - 15 + 4

= 13 - 15

= -2.

∴ 2 must be added to f(X) such that (x-3) is a factor  of 

f(x) .

Answer 2

Answer:

Correct option is

C

4

5

Given equation is kx

2

−2

5

+4=0

a=k,b=−2

5

,c=4

∴D=b

2

−4ac=(−2

5

)

2

−4×k×4=20−16

We know that a quadratic equation has real and equal roots, if D=0.

⇒20−16k=0

⇒−16k=−20

⇒k=

16

20

=

4

5