Lê Thanh Bình - THPT Tĩn h Gia 1 Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) ( ) ( ) ( ) *, 1 2 1.2 2.3 1 1 3    n n n n n n ∈ + + + + + + = ¥ ) 1. )  !"# $ !"#%&'() *    + "  a n b n = *? ,-. %(/  !"#0n ∈¥ ( ) * " .11.!"#0 2!"  #30    4 n k n kk ∈= = +¥ Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) ( ) ( ) ( ) *, 1 2 1.2 2.3 1 1 3    n n n n n n ∈ + + + + + + = ¥ ( ) 1. 2) * * 1. !"#0 1.!"#0 2!"#3 , % "# 56(/!"#0 + 0 ,2  6 +   k n n n k n k = +∈ ∈ = = ¥ ¥ ( ) ( ) . *, 2) " * 1  1(-7!"#0 !"#0  %    1.!"#0 (6   "# 2!"#30 8.9n n n n kkk ∈ = = +∈ = ¥ ¥ 1" . *.!"#0:.- n ∈ ¥ Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) ( ) ( ) ( ) *, 1 2 1.2 2.3 1 1 3    n n n n n n ∈ + + + + + + = ¥ 1, 2!"#;n • = ( ) *<=6>!"#0 7 ? n k k=• ∈¥ ( ) ( ) ( ) ( ) 1 2 1.2 2.3 **. 1 3 k k k k k + = + + + + + 1!"#06@ 7?n k= + ( ) ( ) ( ) ( ) ( ) ( ) 1.2 2.3 1 2 . 3 1 2 3 1 k k k kk k k + + + + + + =+ + + + <= ( ) ( ) * 2 2 .5 &0⇔ = 1.!"#0, - n = ( ) ( ) ( ) ( ) 1 1. 1 2 . * 3 1 1 1 1+ + + = 5--7A!BB# ( ) ( ) ( ) ( ) ( ) ( ) ( ) 1 1 2 1.2 2.3 3 2 11 2k kk k k k k k k + + + + ++ = + ++ + ++ ( ) ( ) ( ) ( ) ( ) 1 2 3 1 2 1 . 33 k k k k k k + + +   = + + + =  ÷   ( ) *.,-!"#0 CD9=n ∈• ¥ ( ) * ." 5AE=*F&7& =FG 4HDF.  0 I6 A n n ∈ ¥ Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) *.HDF. 0 A n n ∈ ¥ ( ) ( ) ( ) ( ) ( ) " * " 1. 1 . *.  0  % 1. 0 (" !)6;74;J4# (K! 2 30 LM974'   0  :.  D   #  4 - A n n A n n k A n n n n k k A = = = + ∈ ∈ ¥ ¥ ( ) 2 *, 1 3 5 2 1K     n n n ∈ + + + + − = ¥ ( ) ( ) 2 2 2 2 2 4 1 *, 1 3 5 2 1 3 N    n n n n − ∈ + + + + − = ¥ !O()99IM9# = § 1 H2 H2 H3 H3 ( ) ( ) *<=. 0 (/=.IM9PA n n k k= ∈¥ Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) " " .* 3 8,Q'R52S=%* 6 0  n n n n ∈ > ¥ § 1 ('T { } { } 1;2 " . 3;3 ; "8 4 5 3 8, 24 6 , 24 0P n n n nn n ∈ >∈> 3 .3"84 0 6U&'()V8  n n n > ≥ 5'8&F9()99IM9W ( ) ( ) *, * &F(HD F. 0  F9()99IM9  + A n n n p p ∈ ∈≥ ¥ ¥ Lê Thanh Bình - THPT Tĩn h Gia 1 § 1 ( ) ( ) ( ) ( ) ( ) ( ) *, . * * ." . 1 , 0X  0 F( 0  <=6> 0 5   F9()99IM9P (" (K 30 :. A n n n p A n n p A n n k p n n k k k A p ∀ ∈ ≥ = = + ∈ ≥ = ∈ ¥¥ ¥ ( ) *, . 0  - A n n n p ∈ ≥ ¥ Lê Thanh Bình - THPT Tĩn h Gia 1 § 1 ( ) ( ) ( ) ( ) ( ) *, 1 " * *, " C F9()99IM98HF()F=6 (" HDF. 0  0 (K P 4 0 A n n n p A p A k A k k k p p ∈ ≥ ⇒ + ∀ ∈ ≥ ∈ ¥¥ ¥ . : %60Y" 6+ ZJ;YK Y+ ( ) ( ) ( ) ( ) 1" * 1 * . 1 2 1 1 1. 1 * . [\6 (6 <=6>!"#0 7 \ =.*!B#7(/ 4    Z!"#30 ,- !"#0 " ! n n n n k k k k k k k k n k = + ∈ = = + + = + + = + + = + ∈ ¥ ¥ *."#0  n ∈ ¥ Lờ Thanh Bỡnh - THPT Tn h Gia 1 Ôn lại lý thuyết, đọc tiếp phần còn lại của bài 1 và làm các bài tập trang 100-101 SGK. Lê Thanh Bình - THPT Tĩn h Gia 1 ( ) ( ) 2 *, 1 3 5 2 1 1   n n n ∈ + + + + − = ¥ 1, 2!"#;n • = ( ) *<=6>!"#0 7 ? n k k=• ∈¥ ( ) ( ) 2 1 3 5 2 1 *k k + + + + − = 1!"#06@ 7?n k= + ( ) ( ) ( ) 2 1 3 5 2 1 2 1 1n n n + + + + − + + = + <= ( ) 2 1 1 .&0= 1.!"#0, - n = 5--7A!B# ( ) ( ) ( ) ( ) 2 2 1 3 5 2 1 2 1 2 1 1n n n n n+ + + + − + + = + + = + ( ) *.,-!"#0 CD9=n ∈• ¥ Re Re [...]...Bài toán: Chứng minh rằng với mọi n Ơ *, ta luôn có n ( 4n 2 1) 2 12 + 32 + 5 + + ( 2n 1) = ( 1) 3 Giải: 2 1 ( 4.1 1) 2 Với n = 1 thì (1) trở thành 1 = ( Hiển nhiên đúng ) 3 Vậy (1) đúng khi n = 1 Re