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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: cho a=-20, b-c=-5 tìm p biết p^2=b(a-c)-c(a-b)

Toán Lớp 7: cho a=-20, b-c=-5 tìm p biết p^2=b(a-c)-c(a-b)

Comments ( 2 )

  1. Ta có:
    $P^{2}$ = b(a – c) – c(a – b)
    $P^{2}$ = ba – bc – ca – cb
    $P^{2}$ = ( ba – ca ) – ( bc – cb )
    $P^{2}$ = ba – ca
    $P^{2}$ = a(b – c)
    $P^{2}$ = -20 . ( – 5 )
    $P^{2}$ = 100
    ⇒ $P^{2}$ = $(±10)^{2}$ 
    ⇒ P = ±10
    Vậy P = ±10

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222-9+11+12:2*14+14 = ? ( )