SAT Math
Systems and Linear Inequalities flashcards
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- Substitute into a target expressionSolving Systems by Substitution
- Solve the pair, then answer the requested combination.
- When should I use direct substitution?Solving Systems by Substitution
- Substitute an isolated variable into another equation.
- What method supports substitute into a target expression?Solving Systems by Substitution
- If y = kx, then ax + by = (a + bk)x
- Isolate before substitutingSolving Systems by Substitution
- Choose the easiest variable to isolate.
- Direct substitutionSolving Systems by Substitution
- Replace the variable with what it equals.
- What must I check in solving systems by substitution?Solving Systems by Substitution
- A solution is an ordered pair satisfying both original equations
- What method supports isolate before substituting?Solving Systems by Substitution
- x + y = s ⇒ y = s − x
- What method supports direct substitution?Solving Systems by Substitution
- y = mx + b and ax + y = c ⇒ (a + m)x + b = c
- When should I use substitute into a target expression?Solving Systems by Substitution
- Find a combination of the solution coordinates.
- When should I use isolate before substituting?Solving Systems by Substitution
- Rewrite one equation to make substitution efficient.
- Eliminate to find a combinationSolving Systems by Elimination
- Look for the target hidden in a sum of equations.
- When should I use immediate elimination?Solving Systems by Elimination
- Add equations whose variable coefficients are opposites.
- What method supports eliminate to find a combination?Solving Systems by Elimination
- If kx + ky = c, then x + y = c/k, k ≠ 0
- Scale and eliminateSolving Systems by Elimination
- Make matching coefficients before canceling.
- Immediate eliminationSolving Systems by Elimination
- Add the equations so one variable disappears.
- What must I check in solving systems by elimination?Solving Systems by Elimination
- Scale every term of an equation before adding; retain signs when subtracting
- What method supports scale and eliminate?Solving Systems by Elimination
- Multiply an entire equation by a nonzero constant
- What method supports immediate elimination?Solving Systems by Elimination
- (ax + by) + (cx − by) = (a + c)x
- When should I use eliminate to find a combination?Solving Systems by Elimination
- Use equation sums to obtain a requested expression directly.
- When should I use scale and eliminate?Solving Systems by Elimination
- Multiply an equation to create canceling coefficients.
- Parameter for a coincident lineGraphical Solutions and Number of Solutions
- Every term must scale by the same factor.
- When should I use unique intersection?Graphical Solutions and Number of Solutions
- Identify when two linear graphs meet once.
- What method supports parameter for a coincident line?Graphical Solutions and Number of Solutions
- Ax + By = C and kAx + kBy = kC describe the same line, k ≠ 0
- Parallel versus identical graphsGraphical Solutions and Number of Solutions
- Same direction plus a different starting value means no crossing.
- Unique intersectionGraphical Solutions and Number of Solutions
- Different slopes lead to one crossing.
- What must I check in graphical solutions and number of solutions?Graphical Solutions and Number of Solutions
- An intersection must lie on both lines; matching slopes alone do not distinguish parallel from identical lines
- What method supports parallel versus identical graphs?Graphical Solutions and Number of Solutions
- same m, different b ⇒ no solution; same m and b ⇒ infinitely many
- What method supports unique intersection?Graphical Solutions and Number of Solutions
- m₁ ≠ m₂ ⇒ exactly one intersection
- When should I use parameter for a coincident line?Graphical Solutions and Number of Solutions
- Match all coefficients to obtain infinitely many system solutions.
- When should I use parallel versus identical graphs?Graphical Solutions and Number of Solutions
- Classify systems by comparing normalized equations.
- Two rates observed twiceSystems of Equations Word Problems
- Different combinations reveal the individual rates.
- When should I use count and value systems?Systems of Equations Word Problems
- Model a total count and a total value.
- What method supports two rates observed twice?Systems of Equations Word Problems
- ax + by = c and dx + ey = f
- Mixture systemsSystems of Equations Word Problems
- Track total mixture and total ingredient separately.
- Count and value systemsSystems of Equations Word Problems
- Use one equation for how many and another for how much.
- What must I check in systems of equations word problems?Systems of Equations Word Problems
- Unknown counts should be nonnegative integers and must satisfy both contextual totals
- What method supports mixture systems?Systems of Equations Word Problems
- x + y = T; p₁x + p₂y = pT
- What method supports count and value systems?Systems of Equations Word Problems
- x + y = N; ax + by = V
- When should I use two rates observed twice?Systems of Equations Word Problems
- Recover rates from two different resource combinations.
- When should I use mixture systems?Systems of Equations Word Problems
- Use weighted contributions to model a blend.
- Integer constraintsLinear Inequalities in One Variable
- Solve first, then enforce whole-item feasibility.
- When should I use positive coefficient inequalities?Linear Inequalities in One Variable
- Solve and interpret a one-variable inequality.
- What method supports integer constraints?Linear Inequalities in One Variable
- x ≤ B/p with integer x ⇒ maximum x = floor(B/p)
- Negative coefficient inequalitiesLinear Inequalities in One Variable
- Dividing by a negative flips the arrow.
- Positive coefficient inequalitiesLinear Inequalities in One Variable
- Balance both sides and keep the arrow when dividing by a positive number.
- What must I check in linear inequalities in one variable?Linear Inequalities in One Variable
- Reverse an inequality when multiplying or dividing by a negative number
- What method supports negative coefficient inequalities?Linear Inequalities in One Variable
- −ax < b ⇒ x > −b/a for a > 0
- What method supports positive coefficient inequalities?Linear Inequalities in One Variable
- ax + b ≤ c ⇒ x ≤ (c − b)/a for a > 0
- When should I use integer constraints?Linear Inequalities in One Variable
- Use an inequality to find a feasible integer maximum.
- When should I use negative coefficient inequalities?Linear Inequalities in One Variable
- Reverse direction after division by a negative.
- Maximum feasible integer valueLinear Inequalities in Two Variables and Systems of Inequalities
- Apply all the limits, then choose the largest allowed integer.
- When should I use test an ordered pair?Linear Inequalities in Two Variables and Systems of Inequalities
- Determine whether a point satisfies a linear inequality.
- What method supports maximum feasible integer value?Linear Inequalities in Two Variables and Systems of Inequalities
- ax + by ≤ C ⇒ y ≤ (C − ax)/b when b > 0
- Intersect two half-planesLinear Inequalities in Two Variables and Systems of Inequalities
- A system uses AND: every inequality must be true.
- Test an ordered pairLinear Inequalities in Two Variables and Systems of Inequalities
- Plug in the point and test the statement.
- What must I check in linear inequalities in two variables and systems of inequalities?Linear Inequalities in Two Variables and Systems of Inequalities
- A boundary line is included for ≤ or ≥ and excluded for < or >; a system requires all conditions
- What method supports intersect two half-planes?Linear Inequalities in Two Variables and Systems of Inequalities
- solution region = intersection of individual solution sets
- What method supports test an ordered pair?Linear Inequalities in Two Variables and Systems of Inequalities
- (a,b) satisfies y > mx + c iff b > ma + c
- When should I use maximum feasible integer value?Linear Inequalities in Two Variables and Systems of Inequalities
- Combine linear inequalities and discrete restrictions.
- When should I use intersect two half-planes?Linear Inequalities in Two Variables and Systems of Inequalities
- Require a point to satisfy every inequality in a system.
