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

Toán Lớp 6: Bài 4 : 2) 2^7 . 9^3 / 6^5 . 8^2 3) 6^3 +3 . 6^2 + 3^3 / -26 4) 81. (27+ 9^15) : (3^5 + 3^32) * “/”

Toán Lớp 6: Bài 4 :
2) 2^7 . 9^3 / 6^5 . 8^2 3) 6^3 +3 . 6^2 + 3^3 / -26
4) 81. (27+ 9^15) : (3^5 + 3^32)
* “/” là dạng phân số nha!
Bài 5:Tìm số nguyên x, biết:
2) x^2=81 3) x^4=625 4) x^2+1=17 5) x^4 – 20=61

Comments ( 1 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    4.
    4_2) (2^7. 9^3)/(6^5. 8^2)
    =(2^7. (3^2)^3)/((2.3)^5. (2^3)^2
    =(2^7. 3^6)/(2^5. 3^5. 2^6
    =(2^7. 3^6)/(2^11. 3^5)
    =(2^7. 3^5. 3)/(2^7. 2^4 .3^5
    =3/(2^4)
    =3/16
    4_3) (6^3+3. 6^2+3^3)/-26
    =(6^2.(6+3)+3^3)/-26
    =(6^2. 9+3^3)/-26
    =(6^2. 3^2+3^3)/-26
    =(3^2.(6^2+3))/-26
    =(3^2. 39)/-26
    =(9.3)/-2
    =(-27)/2
    4_4) (81.(27+9^15))/(3^5+3^32)
    =(3^4.(3^3+(3^2)^15))/(3^5+3^32
    =(3^7+3^34)/(3^5+3^32)
    =(3^7.(1+3^27))/(3^5.(1+3^27))
    =(3^7)/(3^5
    =3^2
    =9
    5.
    5_2) x^2=81
    =>x^2=(+-9)^2
    =>x =+-9
    Vậy x=+-9.
    5_3) x^4=625
    =>x^4=(+-5)^4
    =>x=+-5
    Vậy x=+-5.
    5_4) x^2+1=17
    =>x^2=16
    =>x^2=(+-4)^2
    =>x=+-4
    Vậy x=+-4.
    5_5) x^4-20=61
    =>x^4=81
    =>x^4=(+-3)^4
    =>x=+-3
    Vậy x=+-3.

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