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Help with quadratic functions - sum and roots questions! (1 Viewer)

107thbarnes

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well i'm pretty awful at this topic, so help pleaasse!

1. In the quadratic equation x^2 + mx + 2 = , the roots are consecutive. Find the values of m.


2. In the quadratic equation -3x^2 - (k+1)x + 5=0, the roots are equal in magnitude but opposite in sign. Find the value of k.
 

Drongoski

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I'll just do Q1:

Let the 2 roots be a and a+1.
.: sum of roots = a + a+1 = 2a + 1 = -m
product of roots: a(a+1) = 2 so that a2 + a - 2 = 0

so that a2 + a - 2 = (a+2)(a-1) = 0 ==> a = 1 or -2

case 1: a = 1. Then m = -(2a+1) = -3 ==> eqn is: x2 - 3x + 2 = (x-2)(x-1) = 0

case 2: a = -2. Then m = -(-4+1) = 3 ==> eqn is: x2 + 3x + 2 = (x+2)(x+1) = 0
 
Last edited:

HeroWise

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k=-1 for q2 cus i said so






lol k DIvide everything by -3

THe roots are A and -A if we add em u get 0

so therefor -(k+1)/3 must be 0
 

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