Mathematics

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If (x ^ 3 + a * x ^ 2 + bx + 6) has (x - 2) as a factor and leaves a remainder 3 when divided by (x-3), find the values of a and b ​
If (x ^ 3 + a * x ^ 2 + bx + 6) has (x - 2) as a factor and leaves a remainder 3 when divided by (x-3), find the values of a and b ​

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  • Answer:

    Hey There!

    Let's solve....

    First let's use the remainder theorem...

    [tex]put \: x - 2 = 0 \\ \boxed{x = 2} \\ \\ f(x) = {x}^{3} + {ax}^{2} + bx + 6 \\ \\ f(2) = 0 = {2}^{3} + {2}^{2}a + 2b \\ + 6 = 0 [/tex]

    [tex]4a + 2b + 6 + 8 = 0 \\ 4a + 2b + 14 = 0 \\ so \: equation \: number \: 1 \: is \\ \boxed{2a + b + 7 = 0}[/tex]

    Now it is given that...

    [tex] {x}^{3} + {ax}^{2} + bx + 6 \\ f(3) \to \: remainder = 3 \\ f(3) = 3 \\ {3}^{3} + {3}^{2}a + 3b + 6 = 3 \\ 27 + 9a + 3b + 6 = 3 \\ 9a + 3b + 30 = 0 [/tex]

    [tex]3a + b + 10 = 0 \\ \\ it \: is \: equation \: number \: 2[/tex]

    So...

    Let's find out the value of a

    [tex]3a + \cancel{b} + 10 = 0 \\ 2a + \cancel{b} + 7 = 0 \\ a + 3 = 0 \\ \\ value \: of \: a \: is \\ \boxed{a = - 3}[/tex]

    Let's find value of b...

    [tex]2a + b + 7 = 0 \\ 2x - 3 + b + 7 = 0 \\ b + 1 = 0 \\ value \: of \: b \: is \\ \boxed{b = - 1}[/tex]

    So a= -3 and b= -1 is the final answer .....

    I hope it is helpful to you..

    Cheers!__________

  • The values of a and b are -3 and -1 respectively

    x³ + ax ²+ bx + 6 has (x - 2) as a factor. Therefore,

    (2)³ + a2²+ 2b + 6 = 0

    8 + 4a + 2b + 6 = 0

    4a + 2b = -14

    x³ + ax ²+ bx + 6 leaves a remainder 3 when divided by (x - 3). Therefore,

    (3)³ + a3²+ 3b + 6 = 3

    27 + 9a + 3b + 6 = 3

    9a + 3b = 3 - 33

    9a + 3b = -30

    Simultaneous equation:

    4a + 2b = -14

    9a + 3b = -30

    2b = -14 -4a

    b = -7 - 2a

    Therefore,

    9a + 3( -7 - 2a) = -30

    9a - 21 - 6a = -30

    3a = -30 + 21

    3a = -9

    a = -9 / 3

    a = -3

    4a + 2b = -14

    4(-3) + 2b = -14

    -12 + 2b = -14

    2b = -14 + 12

    2b = -2

    b = -2 / 2

    b = -1

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