Toán Lớp 6: a) 463+318+137-118 b)21×4^2+21×59+21×5^2 c) 465+[58+(-465)+(-38)]

Question

Toán Lớp 6:  a) 463+318+137-118 b)21×4^2+21×59+21×5^2 c) 465+[58+(-465)+(-38)]

hienthucthu97 · Answer

Answer    a, 463 + 318 + 137 - 118   = (463 + 137) + (318 - 118)   = 600 + 200   = 800   ______________________   b, 21 xx 4^2 + 21 xx 59 + 21 xx 5^2   = 21 xx 16 + 21 xx 59 + 21 xx 25   = 21 xx (16 + 59 + 25)   = 21 xx (75 + 25)   = 21 xx 100   = 2100   ________________________   c, 465 + [58 + (-465) + (-38)]   = 465 + [58 - 465 - 38]   = 465 + 58 - 465 - 38   = (465 - 465) + (58 - 38)   = 0 + 20   = 20

thanhmaianh · Answer

a)   463 + 318 + 137 - 118   = ( 463 + 137 ) + ( 318 - 118 )   = 600 + 200   = 800   b)   21 &times; 4^2 + 21 &times; 59 + 21 &times; 5^2   = 21 &times; 16 + 21 &times; 59 + 21 &times; 25   = 21 &times; ( 16 + 59 + 25 )   = 21 &times; 100   = 2100   c)   465 + [ 58 + ( -465 ) + ( -38 ) ]   = 465 + [ 58 - 465 - 38 ]   = 465 + 58 - 465 - 38   = ( 465 - 465 ) + ( 58 - 38 )   = 0 + 20   = 20