This equation is true for all values of the variable. This is called an identity (many solutions).

p. 983b. 6(y – 5) = 2(10 + 3y) 6y – 30 = 20 + 6y -6y -6y Subtract 6y on both sides -30 20 False (no solution)39. Let d = the number of DVD’s they must sell to

make a profitproduction cost = selling price

1500 + .80d = 1.59d - .80d = -.80d 1500 =.79d .79 .79

d = 1898.7

The company must sell 1,899 DVD’s per day to make a profit.

Let’s do 22.

GEOMETRY

A = lwA = 12x square units

x units

12 units

16 units

x – 2 units

22. Find the value of x so that the rectangles have the same area.

A = lwA = 16 (x – 2)A = 16x – 32 square

units

12x = 16(x - 2) 12x = 16x - 32 -16x -16x_____ -4x = -32 -4 -4 x = 8x needs to be 8 in order for the areas to

be the same.

A = lw A = 8(12) = 96 square units

Example: 6v – 4 = v

8 2 (8) 6v – 4 = v (8) Multiply both

sides by 8 8 2 6v – 4 = 4v -6v -6v Subtract 6v on

both sides -4 = -2v -2 -2 Divide -2 on both

sides 2 = v

Now do 21.21. 6(3a + 1) – 30 = 3(2a – 4)

Exit Slip p. 97 Guided practice 1B under Example

1

HW p. 100 10, 12, 16, 20