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Prelim 2016 Maths Help Thread (1 Viewer)

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eyeseeyou

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How do I do this question

x^2+qx+r=0 is three times the other root. Prove 3q^2=16r

I'm kinda confused when doing the working to the question
 

eyeseeyou

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Given that x=2 is a root of the equation x^2+x+m=0 find the other root and the value of m

FInd the value of k for the equation x^2-(k+2)x+4k=0 if
a. the sum of the roots is 5
b. The product of the roots is 12
c. One root is 2 more than the other root
 

eyeseeyou

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For the parabola y=x^2-(p+q)x+pq (where p>q) find the values of x for which y is greater or equal to 0
 

InteGrand

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FInd the value of k for the equation x^2-(k+2)x+4k=0 if
a. the sum of the roots is 5
b. The product of the roots is 12
c. One root is 2 more than the other root
a) The sum of roots is 5, so k+2 = 5, whence k = 3.

b) The product of roots is 12, so 4k = 12, which implies k = 3.

c) Let the roots be a and a+2, then use sum and product of roots to obtain two equations in two unknowns.
 

eyeseeyou

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I don't get this Q

What is the relation btwn a and b if the graph of y=x^2+ax+b:

a) touches the x axis
b) cuts the x-axis at 2 points
 

eyeseeyou

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Show that the roots of a equation (3m-5)x^2-3m^2x+5m^2=0 for m is in not equal to 3 are rational if m is rational

SHow that the roots of the equarion ax^2-(a+b)x+b=0 for a is not equal to 0 are rational for all rational values of a and b

For what values of m does the quadratic equation x^2+mx+(m+1)^2=0 have 2 roots
 

InteGrand

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Show that the roots of a equation (3m-5)x^2-3m^2x+5m^2=0 for m is in not equal to 3 are rational if m is rational

SHow that the roots of the equarion ax^2-(a+b)x+b=0 for a is not equal to 0 are rational for all rational values of a and b

For what values of m does the quadratic equation x^2+mx+(m+1)^2=0 have 2 roots
For the first two, show that the discriminant is a perfect square.

For the last one, if we want distinct roots, we should set the discriminant to be positive and solve for m.
 

eyeseeyou

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Without actually solving the simultaneous equations, state whether the following pairs of lines intersect are parrallel or coincide

a) x+y-7=0 and x+y-8=0
 
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