Cho hình chóp S.ABCD có đáy là hình chữ nhật tâm O với AB = 2a, BC = a. Các cạnh bên của hình chóp đều bằng nhau và bằng  a 2 . Thể tích khối chóp S.ABCD là:

A.  a 3 3 3

B.  a 3 3 4

C.  a 3 3 2

D.  a 3 3

Trừ 2 vế của 2 ot, ta có \(y^3-x^3+2x^2-2y^2+2\left(y-x\right)=0\)

\(\Leftrightarrow\left(y-x\right)\left(y^2+xy+x^2\right)-\left(y-x\right)\left(2x+2y\right)+2\left(y-x\right)=0\)

\(\Leftrightarrow\left(y-x\right)\left(y^2+x^2+2+xy-2y-2x\right)=0\)

Trong không gian với hệ toạ độ Oxyz, cho đường thẳng d: x - 1 1 = y - 2 2 = z - 3 3 . Mặt phẳng nào dưới đây song song với đường thẳng d?

A. x-2y+z=0.

B. x+2y+3z=0.

C. x-2y+z-1=0.

D. x+2y+3z-14=0.

Read the following passage and choose the best answer for each blank. When Tho was born 10 years ago in Da Nang, Viet Nam, he was diagnosed with cerebral palsy - a medical condition (26) ______ from abnormal brain development that affects muscle coordination and movement. Since Tho was born, his father has worked as a bricklayer and his mother stays at home to care for Tho and his three (27) ______. Although Tho’s physical development had progressed through physical therapy, his parents did not think he could (28) ______ from schooling.        In June 2014, the “Persons with Disabilities Support Programme” worked with commune leadership to persuade Tho’s parents to try (29)______ him in nearby Pham Hong Thai Primary School. As part of its broader effort to expand (30) ______  to education for school – age  children with disabilities not enrolled in schools, the project covered Tho’s school fees, meal allowance, uniforms, school bag and other school supplies. After a semester at Pham Hong Thai Primary School, Tho has (31) ______   significant progress, (32) ______  his first semester tests as well as his classmates. The project has worked with the school to create an individual education plan for Tho and train teachers so they can support his special needs while helping foster an encouraging learning (33)  ______ for him at the school.             For more than two years, the project (34) ______  with local government social welfare agencies and NGOs to offer education opportunities to children with disabilities, (35)     ______ by helping enroll children in special schools or providing alternative education for students unable to attend school.

Question 31:

A. done

B. taken

C. made

D. been brought

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