if a+b+c=5,a^+b^+c^=2a,then find the value of ab +bc+ca​

Question

if a+b+c=5,a^+b^+c^=2a,then find the value of ab +bc+ca​

in progress 0
Josephine 6 days 2021-09-10T11:13:34+00:00 2 Answers 0 views 0

Answers ( )

  1. \huge{\sf{\underline{\red{answer:-}}}}

    ➜Here, we having two equations

    →a + b + c = 12 …(eq.1)

    →a^2 + b^2 + c^ =64 …(eq.2)

    by eq.1 we can calculate the value of a, b & c as

    • a = 12 – b – c
    • b = 12 – a – c
    • c = 12 – a – b

    then we put the value of a in second equation.

    we get,

    →(12 – b – c)^2 + b^2 + c^2 = 64

    after solving this,

    →we get, b^2 + bc + c^2 – 12b – 12c + 40 =0

    by using above equation we calculate the term bc.

    therefore, bc = 12b + 12c – b^2 -c^2 – 40

    similarly by putting the values of b and c in eq.2 we get,

    →ac = 12a + 12c – a^2 – c^2 – 40

    →ab = 12a + 12b – a^2 – b^2 – 40

    and now,

    →ab + bc + ac = (12a + 12b – a^2 – b^2 – 40) + (12b + 12c – b^2 -c^2 – 40) + (12a + 12c – a^2 – c^2 – 40)

    →ab + bc + ac = 24a + 24b + 24c – 2a^2 – 2b^2 – 2c^2 – 120

    →ab + bc + ac = 24( a + b + c ) – 2(a^2 + b^2 + c^) – 120

    by eq.1 and eq.2,

    • ab + bc + ac = 24(12) – 2(64) – 120
    • ab + bc + ac = 40

    hence, ab + bc + ac = 40

    thank uhh ♥️

  2. Answer:

    same as ponaam

    ..

    ………

Leave an answer

Browse
Browse

18:9+8+9*3-7:3-1*13 = ? ( )