Question

3. If x = 1 is a common root of ax2 + ax + 2 = 0 and x2 + x + b = 0, then ab = ?
ax2 + ax + 2 = 0 আৰু x2+ x + b = 0 এই দুয়ােটাই সমীকৰণৰেই যদি x = 1 মূল হয়, তেনেহ'লে
ab = ?
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Answer 1

Solution:

It is given that,

x = 1 is a common root of

ax²+ax+2 = 0 -----(1)

x²+x+b = 0 ----(2)

Substitute x=1 , in given equations,

i) a(1)²+a×1 + 2 = 0

=> a+a+2 = 0

=> 2a+2 = 0

=> 2a = -2

=> a=(-2)/2

=> a = -1

ii ) 1²+1+b = 0

=> 1+1+b = 0

=> 2+b = 0

=> b=-2

Therefore,

a = (-1), b = -2

ab = (-1)(-2) = 2

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