x+2x+4x+...+125x+126x bang cach thu gon cac bieu thuc sau:
thu gon bieu thuc sau:
x+2x+3x+4x+...+125x+126
tinh gia tri bieu thuc sau bang cach hop li:
B=1,3-3,2+5,1-7=8,9-10,8+ .... + 35,5 -37,4+39,3-41,2+43,1
minh tim ra cach lam rui nhung cac ban lam ho minh cach ngan gon nhat nhe
thanh nhieu
x+2x+3x+4x + .... 125x +126x = ?
rut gon cac bieu thuc
2x(2x+1)2 - 3x(x+3)(x-3) - 4x (x+1) 2
Ta có 2x(2x + 1)2 - 3x(x + 3)(x - 3) - 4x(x + 1)2
= 2x(4x2 + 4x + 1) - 3x(x2 - 9) - 4x(x2 + 2x + 1)
= 8x3 + 8x2 + 2x - 3x3 + 27x - 4x3 - 8x2 - 4x
= 8x3 - 3x3 - 4x3 + 8x2 - 8x2 + 2x + 27x - 4x
= x3 + 25x
a oi hinh nhu sai r con +16x2 nua co a , anh tinh lai ho e duoc kh
Kiều Trinh Vũ ko có + 16x2 nhá vì 8x2 - 8x2 = 0 nhá
Rut gon cacc bieu thuc sau : ( 4x - 3 ).( x - 5 ) - 2x ( 2x- 11)
\(\left(4x-3\right).\left(x-5\right)-2x\left(2x-11\right)\)
=\(4x^2-20x-3x+15-\left(4x^2-22x\right)\)
\(=4x^2-20x-3x+15-4x^2+22x\)
\(=-x+15\)
Rut gon bieu thuc sau: 2x*(2x-1)2-3x*(x+3)2-4x*(x+1)2
thu gon bieu thuc sau (2x-1)^3-(3x^2-1)(x-2)-(x+3)^3
Ta có: \(\left(2x-1\right)^3-\left(3x^2-1\right)\left(x-2\right)+\left(x+3\right)^3\)
\(=8x^3-12x^2+6x-1-\left(3x^3-6x^2-x+2\right)+x^3+9x^2+27x+27\)
\(=9x^3-3x^2+33x+26-3x^3+6x^2+x-2\)
\(=6x^3+3x^2+34x+24\)
72.54-(30.5+14.04)=
cac ban thuc hien bieu thuc nay bang 2 cach nhe
Cách 1 :
72,54 - (30,5 + 14,04)
= 72,54 - 44,54
= 28
Cách 2:
72,54 - (30,5 + 14,04)
= 72,54 - 30,5 - 14,04
= 43,04 - 14,04
= 28
C1 : 75.54-30.5-14.04=28
C2; =72.54-44.54=28
72,54 - ( 30,5 + 14,04 ) 72,54 - ( 30,5 + 14,04 )
=72,54 - 44,54 = 72,54 - 30,5 - 14,04
= 28 = 42,04 - 14,04
= 28
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rút gon cac bieu thuc (2x +3) mũ 2-(2x+5) mũ 2
(2x+3)2-(2x+5)2
= 4x2+12x+32-4x2+20x+52
=12x+9-12x-8x-25
=9-8x-25
=(-16)-8x