Systems of Equations Flashcards
6 cards from real Algebra Test practice questions. Tap to flip, then mark Knew It or Still Learning โ missed cards come back until you master them.
Read the first 6 Systems of Equations flashcards as text
Two numbers have a sum of 20 and a difference of 6. What are the numbers?
Answer: 13 and 7
x + y = 20 and x - y = 6 gives 2x = 26, so x = 13 and y = 7.
Solve: 2x + y = 8 and x + 2y = 7
Answer: x = 3, y = 2
Substitute y = 8 - 2x into the second equation: x + 2(8 - 2x) = 7, giving x = 3 and y = 2.
If two equations are identical, the system has:
Answer: Infinitely many solutions
Identical equations describe the same line, so every point on it is a solution.
Solve: 5x + 2y = 20 and y = 5
Answer: x = 2
Substitute y = 5: 5x + 10 = 20, so 5x = 10 and x = 2.
Which method is most efficient when one equation is already solved for a variable?
Answer: Substitution
Substitution is most efficient when a variable is isolated and can be plugged directly into the other equation.
A store sells pens for $1 and notebooks for $3. If someone buys 10 items for $18, how many pens were bought?
Answer: 6
p + n = 10 and p + 3n = 18 gives 2n = 8, n = 4, so p = 6.