Question

If one root of x3 - 12x2 + kx – 18 = 0 is thrice
the sum of remaining two roots then k =
1) 29 2) -29 3) 19 4) 15
i solved, but i got the wrong answer. i got 33​

Answer 1

Answer:

Correct option is 1)29

Step-by-step explanation:

let roots are a,b,3(a+b)

sum of roots −(−12)

4(a+b)=12

a+b=3

product=−(−18)

3ab(a+b)=+18

ab=+2

sum of two at=k

ab+3a(a+b)+3b(a+b)=k

k=2+9a+9b

k=9×3+2

k=29