Find the real values of a so th

1. Find the real values of a so that a2+2a,a2+3a+8,2a+3 are the sides of a triangle.

2. If x=2+21/3+22/3 then the value of x3-6x^2+6x is ?

3. Find the eqn whose roots are two more than the roots of ax^2+bx+c=0 .

4 Answers

1
Vinay Arya ·

(3)The given equation is
ax2+bx+c=0
its roots are -b+√(b2-4ac)2a and -b-√(b2-4ac)2a
The roots of the equation that we have to find are:
-b+√(b2-4ac)a and -b-√(b2-4ac)a
The required equation is x2-(sum of roots)x+product of roots=0
x2+2bax+4c=0

30
Ashish Kothari ·

2. x= 2 + 21/3 + 22/3

x3- 6x2 + 6x = (x3- 6x2 + 12x - 8) + 8 - 6x

= (x - 2)3 - 6x + 8

= (21/3 + 22/3)3 - 6(2 + 21/3 + 22/3) + 8

= 2 + 22 + 6(21/3 + 22/3) - 6(2 + 21/3 + 22/3) + 8

= 2

1
ajoy abcd ·

1.Use cosine rule...
then:
-1<cos ∂<1

36
rahul ·

For the first one... use the fact that,

the sum of two sides of a triangle is always greater than the third side.

For the second one... lemme do this....

x = 2 + 21/3 + 22/3 = 21/3 (1 + 21/3 + 22/3)

=> x3 = 2 (x - 1)3

=> x3 = 2 (x3 - 1 - 3x2 + 3x)

=> x3 = 2x3 - 6x2 + 6x - 2

=> x3 - 6x2 + 6x = 2 Ans...

For the third one...

Use this,

If the roots of the first eqns are a1,b1 then the roots of the second eqn.. will be (a1 + 2) and (b1 + 2)

and, quadratic equation with the roots m and n is given by

x2 - (m + n)x + mn done... !!

Your Answer

Close [X]