15. Find two positive integers whose sum is 24 and a product of 140.
a. 16 and 8
b. 14 and 10
c. 20 and 4
d. 21 and 3​


Sagot :

Answer:

B. 14 and 10

Solution:

x + y = 24

x(y) = 140

Since x + y = 24, thus y = 24 - x

Substitute x for y

x(24-x) = 140

Expand the expression

24x - x^2 = 140

Subtract 140 to both sides.

24x - x^2 - 140

Rearrange the equation to the form of [tex]ax^2 + bx + c[/tex] which can be solved using quadratic formula [tex]x = \frac{-b±\sqrt{b^2-4ac} }{2a}[/tex]

[tex]-x^2 + 24x - 140[/tex]

Thus, a = -1, b = 24 and c = -140

Substitute the value

[tex]x=\frac{-24±\sqrt{24^2-4(-1)(-140)} }{2(-1)}[/tex]

[tex]x=\frac{-24±\sqrt{576-560} }{-2}[/tex]

[tex]x = 10[/tex] or [tex]x = 14[/tex]

Therefore the integers are 10 and 14

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