98x57+98x42+98=?
98x42-50[(18-2^3):2+3^2]
98x42-50[(18-2^3):2+3^2]
=98x42-50[(18-8):2+9]
=98x42-50(10:2+9)
=98x42-50(5+9)
=98x42-50x11
=4704-550
=4154
98x42-{50x[18-2^3:2+3^2
98 x 42 - { 50 x [18 - 2 ^ 3 : 2 + 3 ^ 2] }
= 4116 - { 50 x [18 - 8 : 2 + 9] }
= 4116 - { 50 x [18 - 4 + 9] }
= 4116 - { 50 x 23 }
= 4116 - 1150
= 2966
9+8+9+8+9+8+98+98+98+98+98+89+89+9
bằng 728 nha bạn
98 nhân 98 + 98 + 98
So sánh :
C= \(\dfrac{98^{99}+1}{98^{89}+1}\) và D = \(\dfrac{98^{98}+1}{98^{88}+1}\)
\(C-D=\dfrac{\left(98^{99}+1\right)\left(98^{88}+1\right)-\left(98^{89}+1\right)\left(98^{98}+1\right)}{\left(98^{89}+1\right)\left(98^{88}+1\right)}\)
\(=\dfrac{98^{187}+98^{99}+98^{88}+1-98^{197}-98^{89}-98^{98}-1}{\left(98^{89}+1\right)\left(98^{88}+1\right)}\)
\(=\dfrac{98^{99}-98^{98}+98^{88}-98^{89}}{\left(98^{89}+1\right)\left(98^{88}+1\right)}=\dfrac{98^{98}\left(98-1\right)-98^{88}\left(98-1\right)}{\left(98^{89}+1\right)\left(98^{88}+1\right)}\)
\(=\dfrac{97.98^{98}-97.98^{88}}{\left(98^{89}+1\right)\left(98^{88}+1\right)}=\dfrac{97.98^{88}\left(98^{10}-1\right)}{\left(98^{89}+1\right)\left(98^{88}+1\right)}>0\)
\(\Rightarrow C>D\)
De bai: So sánh.C=98^99+1/98^89+1; D=98^98+1/98^88+1.
C=98^99+1/98^89+1 va D=98^98+1/98^88+1. So sanh C va D
C=98^99+1/98^89+1 va D=98^98+1/98^88+1. So sanh C va D
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#C > D
18 - 35 + 98 - 97 + 54 - 98 - 98 + 65 - 89 + 12 - 43 + 89 + 98