Giúp mk nha😘😘
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ta có: 33 + 34 + 35 + 36 + ...+ 339 + 340
= (33+34) + (35 + 36) + ...+ (339 + 340)
= 33.(1+3) + 35.(1+3) + ...+ 339.(1+3)
= 33.4 + 35.4 + ...+ 339.4
= 4.(33+35 + ....+ 339) chia hết cho 4
Viết dưới dạng phân số, ta được \(\frac{35,5}{x}-\frac{2,5}{x}=15\)
\(\frac{35,5-2,5}{x}=15\)
\(\frac{33}{x}=15\)
\(35:x=15\)
\(x=35:15=\frac{35}{15}=\frac{7}{3}\)
Bài 2:
a: Ta có: \(\sqrt{4-2\sqrt{3}}-\sqrt{3}\)
\(=\sqrt{3}-1-\sqrt{3}\)
=-1
b: Ta có: \(\sqrt{11-6\sqrt{2}}-3+\sqrt{2}\)
\(=3-\sqrt{2}-3+\sqrt{2}\)
=0
c: Ta có: \(\sqrt{9-4\sqrt{5}}-2\sqrt{5}\)
\(=\sqrt{5}-2-2\sqrt{5}\)
\(=-\sqrt{5}-2\)
d: Ta có: \(\sqrt{29+4\sqrt{7}}-\sqrt{11-4\sqrt{7}}\)
\(=2\sqrt{7}+1-2+\sqrt{7}\)
\(=3\sqrt{7}-1\)
đánh ra đi bạn, t làm cho :)) ngo thi hoa
1_The water was very dirty. We decided not to go swimming
2_ I was very tired. I went to bed at 7 o'clock
3_ The House was very old. We Couldn't Be In
4. The movie was boring. We went home before In finished
5_ the air was very Fresh. We decide to stay for a long time
6- because the weather was cold, We had to cancel our picnic
7_ some of the book are important . I must read them.
_________Phần còn lại b xem ở phía trên hình ảnh giùm mk nhé