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SOLVE FOR THE VALUES OF DISCRIMINANT AND WRITE THE NATURE OF THE ROOTS OF THE FOLLOWING QUADRATIC EQUATIONS, SHOW YOUR SOLUTIONS

1. x^2 + 9x + 20 = 0
2. 2x^2 - 10x + 8 =0


Sagot :

Nature of roots of a quadratic equation

#1

[tex]\sf x^{2} + 9x + 20 = 0\\\sf a = 1 ; b = 9 ; c = 20\\\sf b^{2} -4ac - 9^{2} -4(1)(20)=81 -80=1[/tex]

Discriminant 1 is not a perfect square

Discriminant: [tex]\bold b^{2} - \bold 4 \bold a \bold c \bold > \bold 0[/tex]

Nature of discriminant: The roots are real,distinct and rational

#2

[tex]\sf 2x^{2} -10x +8=0\\\sf a=2; b=-10; c=8\\\sf b^{2} -4ac =(-10)^{2} -4(2)(8) = 100 - 64 = 36[/tex]

Discriminant 36 is a perfect square

Discriminant: [tex]\sf b^{2} - 4ac > 0[/tex]

Nature of discriminant: The roots are real, distinct and rational