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Simultaneous equations

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교육자를 위해: Simultaneous equations(Mathematics, Algebra)을(를) 위한 바로 쓸 수 있는 수업 슬라이드, 복습 노트 — 수업에 사용하거나, 학습자들이 실시간 게임으로 즐기는 인터랙티브 클래스 활동으로 진행하세요.

수업 노트

What simultaneous equations are

  • Simultaneous equations are two or more equations that share the same unknowns; the solution satisfies all of them at once.
  • Graphically, each linear equation is a line, and the solution is the point of intersection.
  • Intersecting non-parallel lines have one solution. Distinct parallel lines have none; equations of the same line have infinitely many.

Elimination

  • Make the coefficients of one unknown the same (multiply an equation if needed), then add or subtract to eliminate it.
  • Example: 2x + y = 11 and x - y = 1. Add them: 3x = 12, so x = 4, then y = 3.
  • If the signs are the same, subtract; if opposite, add.

One point satisfies both equations

One point satisfies both equationsO−224681012123456xy2x + y = 11(4, 3)x − y = 1

Substitution

  • Rearrange one equation to make a variable the subject, then substitute into the other.
  • Example: y = 2x + 1 and 3x + y = 11. Substitute: 3x + 2x + 1 = 11, so x = 2, y = 5.

Linear and quadratic pairs

  • When one equation is quadratic (for example y = x2 and y = x + 2), use substitution: x2 = x + 2 gives (x - 2)(x + 1) = 0, so there are two solutions: (2, 4) and (-1, 1).
  • A line and a circle can meet at two points, one (a tangent) or none.

A line and a parabola

A line and a parabolaO−2246810−3−2−11234xy(−1, 1)y = x²(2, 4)y = x + 2

Checking

  • Always substitute your answers into both original equations.

슬라이드

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연습 문제

무료 미리 보기 — 32개 중 8개 문제. 가입하면 전부 볼 수 있어요.
  1. 1.When two simultaneous linear equations have one unique solution, what does it represent graphically?

    Easy
    • Athe gradient
    • Bthe point of intersection
    • Cthe y-intercept
    • Dthe midpoint
  2. 2.Solve x + y = 7 and x - y = 3.

    Easy
    • Ax = 5, y = 2
    • Bx = 2, y = 5
    • Cx = 4, y = 3
    • Dx = 7, y = 0
  3. 3.Solve 2x + y = 9 and x - y = 0.

    Easy
    • Ax = 3, y = 3
    • Bx = 4, y = 1
    • Cx = 2, y = 5
    • Dx = 9, y = 9
  4. 4.Solve 3x + 2y = 12 and x + 2y = 8.

    Easy
    • Ax = 2, y = 3
    • Bx = 3, y = 1.5
    • Cx = 4, y = 0
    • Dx = 1, y = 3.5
  5. 5.Solve y = x + 2 and 2x + y = 11.

    Easy
    • Ax = 3, y = 5
    • Bx = 4, y = 6
    • Cx = 2, y = 4
    • Dx = 5, y = 7
  6. 6.Solve y = 3x and x + y = 8.

    Easy
    • Ax = 2, y = 6
    • Bx = 3, y = 5
    • Cx = 4, y = 4
    • Dx = 1, y = 7
  7. 7.Solve 2x + 3y = 13 and x - y = 1.

    Medium
    • Ax = 3.2, y = 2.2
    • Bx = 4, y = 1
    • Cx = 2, y = 3
    • Dx = 5, y = 1
  8. 8.Solve 3x + 2y = 16 and 5x - 2y = 8.

    Medium
    • Ax = 3, y = 3.5
    • Bx = 2, y = 5
    • Cx = 4, y = 2
    • Dx = 3, y = 3

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