# EIV Flashcards

Whether 2 equations involving 2 variables will be sufficient to solve for the variables

If both equations are linear - that is if there are no squared terms and no (xy) terms - the equations will be sufficient unless the two equations are mathematically identical

Whether 2 equations involving 2 variables will be sufficient to solve for the variables

If there are any non-linear terms in either of the equations (x^2, xy, or x/y), there will usually be two (or more) different solutions for each of the variables and the equations will not be sufficient

x² - y² =

(x+y) (x-y)

x² + 2xy + y² =

(x+y) (x+y)

x² - 2xy +y² =

(x-y) (x-y) or (x-y)²

a² - 1 =

(a+1) (a-1)

Inequalities: When dividing or multiplying by a negative number…

…the inequality sign flips

4 - 3x < 10 =

x > 2

Inequalities: You should never…

…subtract or divide inequalities

Inequalities: You can only…

multiply when you know both variables are positive

3 x LT8 =

LT24

8 + LT2 =

LT10

8 - LT2 =

GT6

6 x LT3 =

LT18

-6 x LT3 =

GT-18