Bài 1: Tính:
a) 5.(125-3.17+21):19+17.4
b)2³.89+3³.89+4³.89+89
c) 21.5-42.3²+63
d) 111-11.9+1
Bài 2: Tìm x:
a) 135-(5x-25)=35
b) 120:(x-3)+36=60
c) x (2 trả lời)
Bài 1: Tính:
a) 5.(125-3.17+21):19+17.4
b)2³.89+3³.89+4³.89+89
c) 21.5-42.3²+63
d) 111-11.9+1
Bài 2: Tìm x:
a) 135-(5x-25)=35
b) 120:(x-3)+36=60
c) x (2 trả lời)
1a) 5.(125-3.17+21):19+17.4
= 5.95:19+17.4
= 5.5+68
= 25+68
= 93
1b) 2 mũ 3 x 89 + 3 mũ 3 x 89 + 4 mũ 3 x 89 + 89 (Theo đề bài)
= 8.89+27.89+64.89+89
= 89.(8+27+64+1)
= 89.100
= 8900
1c)21.5-42. 3 mũ 2 + 63 (Theo đề bài)
= 21.5-42.9+63
= 105-378+63
= (-273)+63
= -210
1d) 111-11.9+1
= 111-99+1
= 12+1
= 13
2a) 135-(5x-25)=35
5x-25=135-35
5x-25=100
5x=100+25
5x=125
x=125:5
x= 25
2b) 120:(x-3)+36=60
120:(x-3)= 60-36
120:(x-3)=24
x-3=120:24
x-3=5
x=5+3
x= 8
2c) x (2 trả lời)
x (1)= 25
x (2) = 8
Chúc bạn học tốt
Đáp án:
Bài 1:
a) 5.(125-3.17+21):19+17.4 =
5.(125-51+21):19+51
= 5.(125-51+21):19+51
= 5.95 :19 +51 = 475 : 19 +51
= 25+51
= 76
b)2³.89+3³.89+4³.89+89
= 8.89+27.89+63.89+89.1
= 89.(8+27+64+1)
= 89.100
= 8900
c) 21.5-42.3²+63
= 21.5-42.9+63
= 110-378+63
= -268+63
= -205
d) 111-11.9+1
= 111-99+1
= 12+1
= 13
Bài 2:
a) 135-(5x-25)
=135-35 5x-25
= 100 5x
= 100+25 5x
= 125 x
= 125:5 x
= 25
b) 120:(x-3)+36
=60 120:(x-3)
= 60-36 120:(x-3)
= 24 x-3 = 120 : 24 x-3
= 5 x
= 5+3
=8