Anonymous asked in Science & MathematicsMathematics · 8 years ago

Maths helps with k constants and simultaneous equations?

I need help with the following questions. It would be appreciated if the method and answer were given, so I have a better understanding of how to work out these types of questions.

1.Solve the simultaneous Equations:



2. f(x)=x^2+(k+3)x+k

where k is a real constant

(a) Find the discriminant of f(x) in terms of k

(b) Show that the discriminant of f(x) can be expressed in the form (k+a)^2+b, where a and b are integers to be found.

(c) show that, for all values of k, the equation f(x) = 0 has real roots



1 Answer

  • Anonymous
    8 years ago
    Best Answer


    x + y = 2

    (2y)² - x² = 11

    Difference of two squares is 11 so they are 25 and 36.

    So 2y=6 or -6 and x=5 or -5.

    So x = 5 and y = -3 or x = -5 and y = 3


    (a) Discriminant = (k+3)²-4k

    = k² + 2k + 9

    (b) Discriminant = k² + 2k + 1 + 8 = (k+1)² + 8

    (c) (k+1)² cannot be less than 0 so (k+1)²+8 is always positive so there are two real roots.

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