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Bộ 23 đề thi thử THPTQG năm 2018 - Môn Toán - Gv Đặng Việt Đông - Lovebook - Có lời giải chi tiết

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Đề <strong>thử</strong> sức số 5<br />

The best or no<strong>thi</strong>ng<br />

( A )<br />

3 log 2020 A = log 2017 + log 2021 4 .<br />

2017 2016<br />

Vậy A2017 ( log 2020;log 2021)<br />

.<br />

Câu 50: Đáp án C.<br />

3<br />

4 h<br />

<br />

<br />

3 2 <br />

3<br />

<br />

2 2<br />

Ta có Vbi = Vmc = . ; Vcoc = Vnc<br />

= . h.<br />

( R + r + Rr )<br />

2 2 4<br />

nc<br />

=<br />

mc<br />

do vậy h( R r Rr)<br />

Mà V 2V<br />

R + r + R.<br />

r = h<br />

2 2 2<br />

2 2<br />

2<br />

Mà h ( R r) ( R r)<br />

= + − − do vậy<br />

h<br />

<br />

+ + = 2. . <br />

3 3 2<br />

<br />

r +<br />

2<br />

r r<br />

=<br />

<br />

R<br />

PT − 3 + 1 = 0 <br />

R R r −<br />

=<br />

R<br />

Vậy ta chọn C.<br />

3 5<br />

2<br />

3 5<br />

2<br />

( tm)<br />

( l)<br />

3<br />

.<br />

LOVEBOOK.VN | 26

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