... 25 20 + 3x = 12 5 0 ,25 x = 28 0 ,25 3x= x= 35 0 ,25 Câu 3: (1. 5 điểm) a) 72 = 23 . 32 b/ 36 =22 . 32 90= 2. 32. 5 10 8= 22 .33 (0,5) Sai kết -0 ,25 ƯCLN( 72; 90 ;10 8) =2. 32= 18 (0 ,25 ) (0 ,25 ) 48 =24 .3 16 0 = 25 .5 ... 300 + 800 =11 00 (0 ,25 +0 ,25 +0 ,25 ) b/ 92. 87 + 92. 28 – 92 .15 = 92( 87 +28 – 15 )= 92 .10 0 = 920 0 (0 .25 +0 ,25 +0 ,25 ) c/ 860:858 + 2. 23 – 32. 5 = 82 +24 – 9.5 = 64 +16 – 45 = 35 (0 ,25 +0 ,25 +0 ,25 ) d/ 18 ... = + =2- 1= 1 9 4 4 9 11 11 b / 1 5 5 3 5 a/ c / 28 9 16 9 25 6 19 6 =17 -13 +16 -14 =6 d/ 315 . 21 8 .54 315 . 21 8 .54 3 14 14 14 5 2. 5 10 10 0.75đ 0.75đ...