Đáp án:
\(ĐKXĐ:\begin{cases}a \ge 0\\\sqrt{a}-3 \ne 0\\\end{cases}\)
`<=>` \(\begin{cases}a \ge 0\\\sqrt{a} \ne 3\\\end{cases}\)
`<=>` \(\begin{cases}a \ge 0\\a \ne 9\\\end{cases}\)
`(9-a)/(sqrta+3)-(9-6sqrta+a)/(sqrta-3)-6`
`=(3^2-(sqrta)^2)/(sqrta+3)-(3^2-2.3.sqrta+(sqrta)^2)/(sqrta-3)-6`
`=((3-sqrta)(3+sqrta))/(sqrta+3)-(sqrta-3)^2/(sqrta-3)-6`
`=3-sqrta-(sqrta-3)-6`
`=3-sqrta-sqrta+3-6`
`=-2sqrta`.
Giải thích các bước giải:
`(9-a)/(\sqrt{a}+3)-(9-6\sqrt{a}+a)/(\sqrt{a}-3)-6(ĐKXĐ:a>=0;a ne9)`
`=(3^2-\sqrt{a}^2)/(\sqrt{a}+3)-(3^2-2.3.\sqrt{a}+\sqrt{a}^2)/(\sqrt{a}-3)-6`
`=[(3-\sqrt{a})(3+\sqrt{a})]/(\sqrt{a}+3)-(3-\sqrt{a})^2/(\sqrt{a}-3)-6`
`=[(3-\sqrt{a})(\sqrt{a}+3)]/(\sqrt{a}+3)+(3-\sqrt{a})^2/(3-\sqrt{a})-6`
`=3-\sqrt{a}+3-\sqrt{a}-6`
`=-2\sqrt{a}`
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191. Mami, mami, Miu is sick. She doesn’t eat _ _ _ _ _ _ _ _ . 192. She’s out at the _ _ _ _ _ _ . Please call back later. 193. Last Sunday, he went to the countryside by…………………….(nghe) 194. They often eat _ _ ice cream after dinner. 195. She was fond _ _ fine art. 196. The school …………………….rings at 8.45 AM. 197. What _ _ _ _ _ playing basketball this afternoon? – Good idea. 198. Phong is _ _ _ _ _ _ _ his story and we are listening to him. 199. There will _ _ more computers in classrooms in the future. 200. Every day my sister and brother ……………….. A. does the housework B. do homework C. does the homework D. does homework’s
1. My family - go on a holiday - Ho Chi Minh City - next month. 2. His hair - get longer, so he - have his hair cut - tomorrow. 3. I - attend - my friend's wedding - this weekend. 4. Lisa - not come - my birthday party - this Saturday. 5. Minh - go to university - five years.
tam giác ABC nhọn nội tiếp (O) có đường cao AD,E ,F là hình chiếu của D trên AC,AB a) Gọi M là hình chiếu của D trên AO.chứng minh DMEF là hình thang cân, b) Vẽ (I) đường kính AD cắt (O) tại điểm thứ hai K, AK cắt BC tại H. chứng minh H,E,F thẳng hàng
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152. Is that her brother? – Yes, _ _ _ name is Thomas. 153. Why don’t we go to the _ _ _ _ _ this Sunday? 154. ………….. - I’m tired. A. How are you feel. Ken? B. How do you feel, Ken? C. How can you feel, Ken? D. How would you feel, Ken? 155. A. father B. car C. care D. park 156. like / in autumn ? / is / the weather / What ................................................................................................................................................... 157. like a / would / chocolate. /I / box of ................................................................................................................................................... 158. What’s the weather _ _ _ _ in spring in Paris? 159. My little son’s classmate is _ _ the second floor. 160. Hurry up, or we are late ……………….school. A. for B. to C. at D. in 161. What time will you arrive ……………the station? – 8 a.m. A. to B. in C. at D. on 162. has an / library. / The / school / excellent ................................................................................................................................................... 163. Janes wants to go out tonight but she has got too _ _ _ _ work to do. 164. Does your class _ _ _ _ forty-five students? 165. My school is at……………………… A. 30 Hoang Hoa Tham Road B. Hoan Kiem District C. a village far frrom here D. Nam Dinh province 166. Selena eats …………………..every morning. A. a big breakfast B. a bowls of noodles C. rice D. All are correct 167. STA_P 168. _ _ _ _ you go to church with me this Christmas? 169. Dolphins can’t live in _ _ _ _ _ _ _ _ water, but a lot of the sea is polluted. (nghe) 170. When do you have math? – We have it _ _ Mondays. 171. His job is designing buildings. He is a(n)………………………….. 172. You can’t ………………………..over the wall. It’s too high. (nghe) 173. Thanks for your helping me carry that box? - _ _ pleasure. 174. The other _ _ _ _ of Thanksgiving Day is Turkey Day. 175. Mathew won’t _ _ fishing with his friends. 176. My father gave up smoking be_ _ _ _ _ of his coughs. 177. It’s four _ _ _ _ _ _ . 178. _ _ one in my class is taller than Anh. 179. Princess Merida has long _ _ _ _ _ red hair. 180. They run down…………………..(nghe) 181. Hong likes to help her parents _ _ _ _ the farm work. 182. Can you go to the supermarket to buy some _ _ _ _ _ _es. 183. LA_GE 184.Joe has a ………………………..cake on his birthday? (nghe) 185. There’s _ _ milk left. You should go to the market to buy some. 186. What’s the weather like today? – It’s _ _ _ _ _ . 187. BI_TH 188. There are a lot of ……………………….under the tree. (nghe) 189. Don’t t_ _ _ _ trash in the street. 190. Their house is _ _ _ _ _ _ _ a toy store and a bookstore.
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