Equations With Variables on Both Sides Ms. Turk, Algebra I Unit 2-4
Check Skills You’ll Need 6x - 2x = 2x - 6x = 5x - 5x = -5x + 5x = 4x + 3 = -5 4x -4x x = -2
Example A: 6x + 3 = 8x - 21 x = 12 6x + 3 = 8x - 21 - 6x - 6x + 21 + 21 24 = 2x 2 2 x = 12 6x + 3 8x - 21
Example B: -6d = d + 21 -6d = d + 21 - d - d -7d = 21 -7 -7 d = -3
Example C: m - 8 = 3m m - 8 = 3m - m - m -8 = 2m 2 2 -4 = m
This equation is called an identity. Example D: 10 - 8a = 2(5 - 4a) 10 - 8a = 2(5 - 4a) 10 - 8a = 10 - 8a + 8a + 8a 10 = 10 Always true! This equation is called an identity.
This equation is an identity. Example E: 2(x - 4) = 2x - 8 2(x - 4) = 2x - 8 2x - 8 = 2x - 8 - 2x - 2x -8 = -8 Always true! This equation is an identity.
Identity An equation that is true for every value of the variable. The equation 3x = 3x is an identity.