2x2 + 7x - 15 = 0
If r and s are two solutions of the equation above
and r>s, which of the following is the
value of r-s?

Respuesta :

Answer:

13/2

Step-by-step explanation:

r>s⇒r-s>0

sum of roots=r+s=-7/2

product of roots=rs=-15/2

(r+s)²-(r-s)²=4rs

(-7/2)²-(r-s)²=4×(-15/2)

49/4+30=(r-s)²

(49+120)/4=(r-s)²

(r-s)²=169/4

r-s=√(169/4)=13/2

The value of r - s from the solutions of the quadratic equation is 6.5.

The given equation;

2x² + 7x - 15 = 0

The two solutions of the given quadratic equation is obtained by solving the equation using formula method as shown below;

a = 2, b = 7, c = -15

[tex]x = \frac{-b \ \ +/- \ \ \sqrt{b^2 - 4ac} }{2a} \\\\x = \frac{-7 \ \ + /- \ \ \sqrt{(7)^ - 4(2\times -15)} }{2(2)} \\\\x= \frac{-7 \ \ +/- \ \sqrt{169} }{4} \\\\x = \frac{-7 \ \ +/- \ \ 13}{4} \\\\x = 1.5 \ \ \ or \ \ -5[/tex]

Since r > s

r = 1.5 and s = -5

Then, r - s = 1.5 - (-5) = 1.5 + 5 = 6.5

Thus, the value of r - s from the solutions of the quadratic equation is 6.5.

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