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    If m = -9 and n = 13, find the value of 25m2 + 40mn +16n2
    Question

    If m = -9 and n = 13, find the value of 25m2 + 40mn +16n2

    A.

    64

    B.

    49

    C.

    81

    D.

    100

    Correct option is B

    Given:

    m = -9, n = 13.

    Solution:

    25m2+40mn+16n2=(5m+4n)225m^2 + 40mn + 16n^2 = (5m + 4n)^2 

    Then, 

    5m+4n=5(9)+4(13)=45+52=75m + 4n = 5(-9) + 4(13) = -45 + 52 = 7 

    So, 

    (5m+4n)2=72=49.(5m + 4n)^2 = 7^2 = 49. ​​

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