Question

câu 11:tính nhanh

a, (1+2+3+...+99)x(13x15-12x15-15)

cách giải

Answer 1

a, (1+2+3+...+99)x(13x15-12x15-15)
= (1+2+3+...+99)x(195-180-15)
= (1+2+3+...+99)x0
= 0

Answer 2

^{_{a, ( 1 + 2 + 3 + ... + 99 ) x ( 13 x 15 - 12 x 15 - 15)
= ( 1 + 2 + 3 + ... + 99 ) x ( 195 - 180 -15 )
= ( 1 + 2 + 3 + ... + 99 ) x 0
= 0}}