Đặt \(x^2+x+1=t\)

\(\left(x^2+x+1\right)\left(x^2+x+2\right)-12=t\left(t+1\right)-12=t^2+t-12=\left(t^2+t+\dfrac{1}{4}\right)-\dfrac{49}{4}=\left(t+\dfrac{1}{2}\right)^2-\left(\dfrac{7}{2}\right)^2=\left(t+\dfrac{1}{2}-\dfrac{7}{2}\right)\left(t+\dfrac{1}{2}+\dfrac{7}{2}\right)=\left(t-3\right)\left(t+4\right)=\left(x^2+x-2\right)\left(x^2+x+5\right)\)

\(\left(x^2+x+1\right)\left(x^2+x+2\right)-12\)

= \(\left(x^2+x+1\right)\left[\left(x^2+x+1\right)+1\right]-12\)

= \(\left(x^2+x+1\right)^2\left(x^2+x+1\right)-12\)

= \(\left(x^2+x+1\right)\left(x^2+x+1\right)-3\left(x^2+x+1\right)+4\left(x^2+x+1\right)-4.3\)

= \(\left(x^2+x+1\right)\left(x^2+x-2\right)+4\left(x^2+x-2\right)\)

= \(\left(x^2+x+5\right)\left(x^2+x-2\right)\)

có  tính 6a ko

kick    tui  đi

mk học lp 6B nhưng là trường THCS Trung Hòa

Tui tự vẽ đó

la cau hoi tuong tu do ban

câu hỏi tương tự nha 

bằng 1,06 nha không dư tick giumg nha

bài này không cần giảng bạn ạ

Trang nè kết quả là 1,06

**** mình nha Trang xinh đẹp

Với \(x\ge1\)

\(\sqrt{x+4}-\sqrt{x-1}=1\)

<=>\(\sqrt{x+4}=\sqrt{x-1}+1\)

<=>\(x+4=x-1+1+2\sqrt{x-1}\)

<=>\(2\sqrt{x-1}=4\)

<=>\(\sqrt{x-1}=2\)

<=>\(x-1=4\)

<=>x=5(TM)

bước tương đương thứ 2 bình phương cả 2 vế

51/ a. did                       b. got                    c. made                          d. bought

52/ a. in                         b. from                 c. by                                d. of

53/ a. said                     b. asked                c. spoke                          d. told

54/ a. special                 b. specially           c. specialty                      d. specialty

55/ a. be                        b. are                    c. was                              d. were

56/ a. fashion                b. fashionable        c. fashionably                 d. fashioners

57/ a see                        b. saw                   c. seen                            d. seeing

58/ a. of                        b. to                      c. an                                d. a

59/ a. out                      b. of                      c. out of                          d. from

60/ a. with                     b. by                     c. of                               d. in