A positive real number is 2 less than another. When 4 times the larger is added to the square of the smaller, the result is 49. Find the numbers

Answer :

calculista

Answer:

The numbers are

[tex]-2+3\sqrt{5}[/tex]   and [tex]3\sqrt{5}[/tex]

Step-by-step explanation:

Let

x -----> the smaller positive real number

y -----> the larger positive real number

we know that

A positive real number is 2 less than another

so

[tex]x=y-2[/tex]

[tex]y=x+2[/tex] ----> equation A

When 4 times the larger is added to the square of the smaller, the result is 49

so

[tex]4y+x^2=49[/tex] ----> equation B

substitute equation A in equation B

[tex]4(x+2)+x^2=49[/tex]

solve for x

[tex]x^2+4x-41=0[/tex]

The formula to solve a quadratic equation of the form

[tex]ax^{2} +bx+c=0[/tex]

is equal to

[tex]x=\frac{-b\pm\sqrt{b^{2}-4ac}} {2a}[/tex]

in this problem we have

[tex]x^2+4x-41=0[/tex]

so

[tex]a=1\\b=4\\c=-41[/tex]

substitute in the formula

[tex]x=\frac{-4\pm\sqrt{4^{2}-4(1)(-41)}} {2(1)}[/tex]

[tex]x=\frac{-4\pm\sqrt{180}} {2}[/tex]

[tex]x=\frac{-4\pm6\sqrt{5}} {2}[/tex]

[tex]x=-2\pm3\sqrt{5}[/tex]

so

The positive real number is

[tex]x=-2+3\sqrt{5}[/tex]

Find the value of y

[tex]y=x+2[/tex]

[tex]y=-2+3\sqrt{5}+2[/tex]

[tex]y=3\sqrt{5}[/tex]

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