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

Toán Lớp 6: a,157 – 4 . ( x + 1 )² b, ( 2x – 1 )²⁰²⁰ = ( 2x – 1 )²⁰¹⁹ c, 5ˣ + ¹ + 5ˣ+² = 750 d, 4ˣ – ¹ + 1²⁰¹⁹ = 257 giúp em vs ạ

Tháng Mười Hai 7, 2022 Toán học 2 Comments 0 views

Toán Lớp 6: a,157 – 4 . ( x + 1 )²
b, ( 2x – 1 )²⁰²⁰ = ( 2x – 1 )²⁰¹⁹
c, 5ˣ + ¹ + 5ˣ+² = 750
d, 4ˣ – ¹ + 1²⁰¹⁹ = 257
giúp em vs ạ

Comments ( 2 )

  1. maingoctruc
    maingoctruc
    7 Tháng Mười Hai, 2022 at 4:37 sáng
    Reply
    $a)157-4(x+1)^{2}$
    $=157-4(x^{2}+2x+1)$
    $=157-4x^{2}-8x-4$
    $=153-4x^{2}-8x$
    $=153-16x^{2}-8x$
    $b)(2x-1)^{2020}=(2x-1)^{2019}$
    $=>(2x-1)^{2020}-(2x-1)^{2019}=0$
    $=>(2x-1)^{2019}[(2x-1)-1]=0$
    $=>(2x-1)^{2019}[2x-1-1]=0$
    $=>(2x-1)^{2019}[2x-2]=0$
    $=>(2x-1)^{2019}=0 hay (2x-2)=0$
    $=>(2x-1)=0 hay 2x=2$
    $=>2x=1 hay x=1$
    $=>x=0,5 hay x=1$
    $c)5^{x+1}+5^{x+2}=750$
    $=>5^{x}.5^{1}+5^{x}.5^{2}=750$
    $=>5^{x}(5^{1}+5^{2})=750$
    $=>5^{x}.30=750$
    $=>5^{x}=25$
    $=>5^{x}=5^{2}$
    $=>x=2$
    $d)4^{x-1}+1^{2019}=257$
    $=>4^{x-1}+1=257$
    $=>4^{x-1}=256$
    $=>4^{x-1}=4^{4}$
    $=>(x-1)=4$
    $=>x=5$
    text{CHÚC BẠN HỌC TỐT. XIN HAY NHẤT.} 

  2. ngoclankhue
    ngoclankhue
    7 Tháng Mười Hai, 2022 at 4:36 sáng
    Reply
    a)157-4(x+1)^2
    =157-4(x^2+2x+1)
    =-4x^2-8x+153
    b)(2x-1)^2020=(2x-1)^2019
    =>(2x-1)^2019(2x-1-1)=0
    =>(2x-1)(2x-2)=0
    =>[(2x-1=0),(2x-2=0):}
    =>[(2x=1),(2x=2):}
    =>[(x=1/2),(x=1):}
    Vậy x=1/2 hoặc x=1.
    c)5^{x+1}+5^{x+2}=750
    =>5^{x+1}(5+1)=750
    =>6.5^{x+1}+750
    =>5^{x+1}=125=5^3
    =>x+1=3
    =>x=2
    Vậy x=2.
    d)4^{x-1}+1^2019=257
    =>4^{x-1}+1=257
    =>4^{x-1}=256
    =>4^{x-1}=4^4
    =>x-1=4
    =>x=5
    Vậy x=5.

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

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