Common Roots

IMPORTANT

Common Roots: Overview

This topic covers concepts, such as, Condition for the Common Roots, Common Root of Two Quadratic Equations, Quadratic Equations with Both Roots Common & Quadratic Equations with Exactly One Common Root etc.

Important Questions on Common Roots

HARD
IMPORTANT

If a, b, cR, then find the relation between a, b, c so that the two quadratic equations ax2+bx+c=0 and 1003x2+1505x+2007=0 have a common root.

MEDIUM
IMPORTANT

If equations x6+ax4-4x=0 and x7+ax5-1=0 have a common root, then identify which of the following statement is(are) correct?

EASY
IMPORTANT

If the equations x2+px+q=0 and x2+rx+s=0 have a common root, show that it must be ps-rqq-s or q-sr-p.

MEDIUM
IMPORTANT

The equations x2-cx+d=0 and x2-ax+b=0 have one common root and the 2nd equation has equal roots. Prove that 2b+d=ac.

EASY
IMPORTANT

Find the value of k for which the equations x2-kx-21=0 and x2-3kx+35=0 have a common root.

MEDIUM
IMPORTANT

If the equation ax2+bx+c=0 and bx2+cx+a=0 (where acb2) have a common root, then show that, either a+b+c=0 or a=b=c.

EASY
IMPORTANT

Show that the equations b-cx2+c-ax+a-b=0 and c-ax2+a-bx+b-c=0 have a common root.

EASY
IMPORTANT

If the quadratic equations x2+ax+b=0 and x2+bx+a=0 (ab) have a common root then find a+b.

HARD
IMPORTANT

If the equations x2+bx+ca=0 and x2+cx+ab=0 have exactly one non-zero common root, then prove that the other roots of the equations satisfy x2+ax+bc=0.

MEDIUM
IMPORTANT

If α, β are the roots of the equation x2+px+q=0 and γ, δ  are the roots of the equation x2+rx+s=0 evaluate (α-γ)(α-δ)(β-γ)(β-δ) in term of p, q, r, s Hence, show that (s-q)2=(r-p)(ps-rq) is the condition for the existence of a common root of the two equations.

MEDIUM
IMPORTANT

If the quadratic equations x2+ax+b=0 and x2+bx+a=0(ab) have a common root then find (a+b).

MEDIUM
IMPORTANT

If the equations ax2+bx+c=0 and  cx2+bx+a=0, where ac have a common root, then a+b+c=0 or a-b+c=0

MEDIUM
IMPORTANT

If the equations x2-11x+k=0 and  x2-14x+2k=0 have a common root, find the sum of possible values of k.

MEDIUM
IMPORTANT

If one root of the equations ax2+bx+c=0 and bx2+cx+a=0a, b, cR is common, then find the value of a3+b3+c3abc3

HARD
IMPORTANT

If x2+3x+5=0 and ax2+bx+c=0 have common root / roots and a, b, cN. then the minimum value of a+b+c is 

MEDIUM
IMPORTANT

If all the equations x2+(2a+3b)x+60=0, x2+ax+10=0 and x2+bx+8=0 where a, bR, have a common root, then value of |a-b| is

MEDIUM
IMPORTANT

If the equation x2+px+2q=0 and x2+qx+2p=0(pq) have a common root
then the absolute value of (p+q) is

MEDIUM
IMPORTANT

If all the equations x2+(2a+3b)x+60=0,x2+ax+10=0 and x2+bx+8=0 where a,bR,have a common root, then value of |a-b| is

HARD
IMPORTANT

If bx2+ax+c=0, ax2+bx+c=0 and ax2+cx+b=0, each equation has equal roots, then 3abc3bac3cab is equal to

HARD
IMPORTANT

For next two question please follow the same  

 If the quadratic equations a1x2 + b1x + c1 = 0 and a2x2 + b2x + c2 = 0 have exactly one common root, then the relation between their coefficients is c 1 a 2 - c 2 a 1 2 = b 1 c 2 - b 2 c 1 a 1 b 2 - a 2 b 1 . If both the roots are common, then the relation between their coefficient is  a 1 a 2 = b 1 b 2 = c 1 c 2 .

 If the equations ax3+3bx2+3cx+d=0 and  ax2+2bx+c=0  have a common root, then which of the following option is correct ?