what is the solution to this system? 3x+2y=45 4x+-y=5

Question

what is the solution to this system?
3x+2y=45
4x+-y=5

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Thanh Hà 5 years 2021-07-22T16:05:34+00:00 1 Answers 33 views 0

Answers ( )

  1. Cherry
    0
    2021-07-22T16:07:13+00:00
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    (I) 3x + 2y = 45

    (II) 4x - y = 5

    Get y alone in equation (II)

    4x - y = 5\\y = 4x - 5

    Insert new equation (II) in equation (I)

    3x + 2(4x - 5) = 45\\3x + 8x - 10 = 45\\3x + 8x = 45 + 10\\11x = 55\\x = 5

    Insert x = 5 in equation (II)

    y = 4 \cdot 5 - 5\\y = 20 - 5\\y = 15

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )