Câu hỏi của daohuyentrang

Question

Tim so tu nhien x biet 2x3 = 1282x - 1 = 219 +218 + 217 + ..... + 2 +1

kudo shinichi · Accepted Answer

$2x^3=128$$x^3=128:2$$x^3=64$$x^3=4^3$$\Rightarrow x=4$Vậy $x=4$Đặt $A=2^{19}+2^{18}+...+2+1$$\Rightarrow2A=2^{20}+2^{19}+...+2^2+2$$\Rightarrow2A-A=\left(2^{20}+2^{19}+...+2^2+2\right)-\left(2^{19}+2^{18}+...+2+1\right)$$A=2^{20}-1$Ta có: $2^x-1=2^{19}+2^{18}+...+2+1$$\Rightarrow2^x-1=2^{20}-1$$\Rightarrow2^x=2^{20}$$\Rightarrow x=20$Vậy $x=20$Tham khảo nhé~Câu trả lời: $2x^3=128$$x^3=128:2$$x^3=64$$x^3=4^3$$\Rightarrow x=4$Vậy $x=4$Đặt $A=2^{19}+2^{18}+...+2+1$$\Rightarrow2A=2^{20}+2^{19}+...+2^2+2$$\Rightarrow2A-A=\left(2^{20}+2^{19}+...+2^2+2\right)-\left(2^{19}+2^{18}+...+2+1\right)$$A=2^{20}-1$Ta có: $2^x-1=2^{19}+2^{18}+...+2+1$$\Rightarrow2^x-1=2^{20}-1$$\Rightarrow2^x=2^{20}$$\Rightarrow x=20$Vậy $x=20$Tham khảo nhé~

Tuan · Answer

2x3=128 x   =2Câu trả lời: 2x3=128 x   =2

nene · Answer

2 x 3 = 128Đáp án : 2 x 43 = 128Câu trả lời: 2 x 3 = 128Đáp án : 2 x 43 = 128

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