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

Toán Lớp 7: f, x^45-x^43=5^42.(5^3-5) g,7^2x+1+7^2x-1=50.72021 h,(x-1).(x+1).(x^2+1).(x^4+1)=255 i, (x^2+2x+1).(x^2+2x+3)=99 k,(x^2+5x).(x^2+5x-2)=

Home/ Toán Lớp 7: f, x^45-x^43=5^42.(5^3-5) g,7^2x+1+7^2x-1=50.72021 h,(x-1).(x+1).(x^2+1).(x^4+1)=255 i, (x^2+2x+1).(x^2+2x+3)=99 k,(x^2+5x).(x^2+5x-2)=

Toán Lớp 7: f, x^45-x^43=5^42.(5^3-5) g,7^2x+1+7^2x-1=50.72021 h,(x-1).(x+1).(x^2+1).(x^4+1)=255 i, (x^2+2x+1).(x^2+2x+3)=99 k,(x^2+5x).(x^2+5x-2)=

Tháng Mười Hai 12, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: f, x^45-x^43=5^42.(5^3-5)
g,7^2x+1+7^2x-1=50.72021
h,(x-1).(x+1).(x^2+1).(x^4+1)=255
i, (x^2+2x+1).(x^2+2x+3)=99
k,(x^2+5x).(x^2+5x-2)=525
giúp mik vs ạ cảm ơn trc

Comments ( 2 )

  1. minhtuyethue
    minhtuyethue
    12 Tháng Mười Hai, 2022 at 12:56 chiều
    Reply
    a. x^45 – x^43 = 5^42. ( 5^3 – 5 )
    => x^42.(x^3 – x) = 5^42.(5^3 – 5)
    => x = 5
    g. 7^2x + 1 + 7^2x – 1 = 50.72021
    => 7^2x = 1800525
    => 2x = $log_{7}$ ( 1800525 )
    => x = $\frac{log7 (1800525)}{2}$ 
    i. (x^2+2x+1).(x^2+2x+3)=99
    => ( x + 1 )^2 [ x ( x + 2 ) +3 ] = 99
    => x^4 + 4x^3 + 8x^2 + 8x – 96 = 0
    => x^4 + 4x^3 + 8x^2 + 8x + 3 = 99
    => x = -4 hoặc x = 2
    k. (x^2+5x).(x^2+5x-2)=525
    => x ( x + 5 ) [ ( x ( x + 5 ) – 2 ] = 525
    => x^4 + 10x^3 + 23x^2 – 10x – 525 = 0
    => x^4 + 10x^3 + 23x^2 – 10x = 525
    => x = 1/2
     

  2. bichhhathu
    bichhhathu
    12 Tháng Mười Hai, 2022 at 12:56 chiều
    Reply
    Đáp án:
     
    Giải thích các bước giải:
     

    toan-lop-7-f-45-43-5-42-5-3-5-g-7-2-1-7-2-1-50-72021-h-1-1-2-1-4-1-255-i-2-2-1-2-2-3-99-k-2-5-2

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

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