Joyslligrace18idn
Answered

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situations where quadratic equations are illustrated

Sagot :

KylJustin09idn
The square of number is decreased by 15. This value is twice the original number. Find the number(s). The answer is:

x-15=2x
x-2x-15=0
(x-5)(x+3)=0
x=5x  x=(-3)
AnneCidn
The most common problems involving quadratic equations are finding the dimensions when the area is given.

Example:

Find the dimensions of a rectangular textbook whose length is 10cm longer than its width and covers an area of 375 cm².

Solution:

Let x be the width of the textbook
      x+10 be the length of the textbook

A = width·length
375 = x (x+10)
375 = x² +10x
    0 = x² +10x -375
    0 = (x+25) (x-15) 
x+25 = 0     ;     x-15 = 0
     x = -25    ;     x = 15           (use x=15 because dimensions may never be negative)

Answer :
              Width = 15 cm
              Length = 25 cm        (from x+10)