Viewing page 42 of 91

This transcription has been completed. Contact us with corrections.

24-25    ARMY AIR FORCES

(2) Example: Evaluate a[(a-b)+c(a²-c)-d(a-c²)] when a=2, b=3, c=4, d=6.

Solution: 2[(2-3)+4(2²-4)-6(2-4²)]=
          2[-1+4(0)-6(-14)]=
          2[-1+0+84]=2[83]=166  Answer.

b. Exercises.–– Evaluate the following if x=3, y=2, z=5.

(1)x(y+2)(3y+x)
(2)4(x²-y) + y²(z-y)     40 Answer.
(3)(y-3x) + z(y-x)  
(4)x(x+y) + z²+x(y-3)    37 Answer.
(5)0[x+y(z-7)+4]-7
(6)z-x/z-y              2/3 Answer.
(7)x+y/y

25.Equations. - a. An equation is a statement of equality between any two quantities. Thus, in reality, all formulas are equations. In most equations that are used, there is an unknown quantity for which a value sought. To find this, certain rules must be followed:

(1) Equal quantities may be added to both sides of the equation.

Example: x -4= 7
           +4= +4
        _____________
           x = 11

(2)Equal quantities may be sybtracted from both sides of the equation.

Example: x +2 = 5
           -2 = -2
       ______________
            x = 3

(3)Both sides of the equation may be multiplied by the same quantity.

Example:  x/2 = 4
          x = 4.2
          x = 8

(4) Both sides may be divided by the same quantity (zero excepted).

Example: 3x= 12
         3x/3 = 12/3
         x = 4


40