Toán Lớp 7: Giúp em với!!!!
4^6 x 9^5 + 6^9 x 120 phần 8^4 x 3^12 -6^11
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Toán Lớp 7: Giúp em với!!!!
4^6 x 9^5 + 6^9 x 120 phần 8^4 x 3^12 -6^11
Comments ( 2 )
{ 4^6 xx 9^5 + 6^9 xx 120 }/{ 8^4 xx 3^{12} – 6^{11} }
= { 2^{12} xx 3^{10} + 2^9 xx 3^9 xx 2^3 xx 3 xx 5 }/{ 2^{12} xx 3^{12} – 6^{11} xx 3^{11} }
= { 2^{12} xx 3^{10} + 2^{12} xx 3^{10} xx 5 }/{ 2^{12} xx 3^{12} – 2^{11} xx 3^{11} }
= { 2^{12} xx 3^{10} xx ( 1 + 5 )}/{ 2^{11} xx 3^{11} xx ( 2 xx 3 – 1 ) }
= { 2^{12} xx 3^{10} xx 6}/{ 2^{11} xx 3^{11} xx 5 }
= { 2^{12} xx 3^{10} xx 2 xx 3}/{ 2^{11} xx 3^{11} xx 5 }
= { 2^{13} xx 3^{11} }/{ 2^{11} xx 3^{11} xx 5 }
= 2^2/5
= 4/5
Giải đáp:
(4^6 xx 9^5 + 6^9 xx 120)/(8^4 xx 3^12 -6^11)
= [(2^2)^6 xx (3^2)^5 + 2^9 xx 3^9 xx 2^3 xx 3 xx5]/[(2^3)^4 xx 3^12 – 2^11 xx 3^11]
= [2^12 xx3^10 + 2^12 xx 3^10 xx5]/[2^12 xx 3^12 – 2^11 xx 3^11]
= [2^12 xx3^10 .(1 + 5)]/[2^11 xx 3^11 .(2 xx 3 – 1)]
= [2^12 xx3^10 .6]/[2^11 xx 3^11 .5]
= [2 xx 6]/[3 xx 5]
= 12/15
= 4/5
$#dariana$