If 1 and -2 are zeroes of x^2+ax+b=0. Find a and b. First and correct answer will be marked brainliest.

Question

If 1 and -2 are zeroes of x^2+ax+b=0. Find a and b. First and correct answer will be marked brainliest.

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Eirian 3 years 2021-07-19T15:57:54+00:00 1 Answers 9 views 0

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  1. danthu
    0
    2021-07-19T15:58:56+00:00
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    Answer:

    a = 1, b = -2

    Step-by-step explanation:

    You are given values of x are 1 and 2 when the equation is 0

    To solve the problem substitute the values of x into the equation

    For x =1

    1^2 + a(1) + b = 0

    1 + a + b = 0

    a+b = -1(call this equation i)

    For x = -2

    -2^2 + a(-2) + b = 0

    4 – 2a + b = 0

    -2a + b = -4 (call this equation ii)

    Now solve equation i and ii simultaneously to get values of a and b.

    a+b = -1

    -2a+b = -4

    By elimination method (also you can solve by substitution method) subtract equation ii from equation i, we get

    3a = 3

    Divide 3 both sides, you get

    a = 1

    Take the value of a above substitute it into either equation i or ii to get the value of b

    Here i considered equation i

    a + b = -1

    1 + b = – 1

    b = – 1 – 1

    b = -2

    Therefore a = 1, b = -2

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