標題:
中一升中二 數學
發問:
此文章來自奇摩知識+如有不便請留言告知
1) If +35km/h means exceeding the speed limit by 35km/h,how do you represent a car at the speed limit exactly? (directed numbers)2) (-11)x(8/33)/(-12)=? 3)there are 20 questions in a maths competition. 5pts are awarded for each correct ans,3pts are deducted for each wrong answer,while 1pt is deducted for each... 顯示更多 1) If +35km/h means exceeding the speed limit by 35km/h,how do you represent a car at the speed limit exactly? (directed numbers) 2) (-11)x(8/33)/(-12)=? 3)there are 20 questions in a maths competition. 5pts are awarded for each correct ans,3pts are deducted for each wrong answer,while 1pt is deducted for each 'pass'.If team A gets 8 questions correct,5 questions wrong and answers the remaining questions with 'pass', find the total pts obtained by team A. 4)The ages of Chris and his father are now 8 and 42. After how many yrs will the age of Chris is 1/3 of that of his father?(Algebra) 5)In a charity sale,the orices of a pencil box and a pack of chocolate are $20 and $50 respectively. If 100 items are sold in total and $3950 is raised,how many pencil box are sold?(Algebra) 6)Mary and Susan have 100 pstcards in total.On Susan's birthday,Mary gives 4/5 of her postcards to Susan.If Susan has 85 postcards now, find the original no. of postcards that Mary has.(Algebra) 7)Solve the equation 1.5[2x-0.6(x+4)]=x+4/2 8)c/4+c/2= -1 c=? 9)Solve the equation 2e+1/3=e-2/4
最佳解答:
Hi ! I am lop****** , feel happy to answer your question. Q 1 : If +35km/h means exceeding the speed limit by 35km/h,how do you represent a car at the speed limit exactly? (directed numbers) A 1 : no ' + ' or ' - ' , 35km/h Q 2 : (-11)x(8/33)/(-12)=? A 2 : (-11)×(8/33)/(-12) = (-8/3)/(-12) = 3(-8/3)/3(-12) = -24/-36 = 24/36 = 2/3 Q 3 : there are 20 questions in a maths competition. 5pts are awarded for each correct ans,3pts are deducted for each wrong answer,while 1pt is deducted for each 'pass'.If team A gets 8 questions correct,5 questions wrong and answers the remaining questions with 'pass', find the total pts obtained by team A. A 3 : The total pts obtained by team A is : 5 × 8 - 3 × 5 - ( 20 - 8 - 5 ) × 1 = 40 - 15 - 7 = 18 pts Q 4 : The ages of Chris and his father are now 8 and 42. After how many yrs will the age of Chris is 1/3 of that of his father?(Algebra) A 4 : Let after x yrs , the age of Chris is 1/3 of that of his father . 8 + x = ( 42 + x ) / 3 3(8+x) = 3(42+x)/3 24+3x = 42+x 24+3x-24=42+x-24 3x=x+18 3x-x=x+18-x 2x=18 2x/2=18/2 x=9 Answer : after 9 yrs , the age of Chris is 1/3 of that of his father . Q 5 : In a charity sale,the orices of a pencil box and a pack of chocolate are $20 and $50 respectively. If 100 items are sold in total and $3950 is raised,how many pencil box are sold?(Algebra) A 5 : Let the number of pencil box are sold is y , the number of packs of chocolate are sold is (100-y) . 20y + (100-y)50 = 3950 20y + 5000 - 50y = 3950 5000 - 30y = 3950 5000 - 30y - 5000 = 3950 - 5000 -30y = -1050 30y = 1050 30y/30 = 1050/30 y = 35 Answer : the number of pencil box are sold is 35 . 2011-08-26 16:43:59 補充： Q 6 : Mary and Susan have 100 pstcards in total.On Susan's birthday,Mary gives 4/5 of her postcards to Susan.If Susan has 85 postcards now, find the original no. of postcards that Mary has.(Algebra) 2011-08-26 16:44:07 補充： A 6 : Let the original no. of postcards that Mary has is a , the original no. of postcards that Susan has is ( 100 - a ) . (100-a) + 4a/5 = 85 5[(100-a)+4a/5]=5×85 500-5a+4a = 425 500 - a = 425 500 - a - 500 = 425 - 500 -a = -75 a = 75 Answer : the original no. of postcards that Mary has is 75 . 2011-08-26 16:44:19 補充： Q 7 : Solve the equation 1.5[2x-0.6(x+4)]=x+4/2 A 7 : 1.5[2x-0.6(x+4)]=x+4/2 1.5(2x-0.6x-2.4)=x+2 1.5(1.4x-2.4)=x+2 2.1x-3.6=x+2 2.1x-3.6+3.6=x+2+3.6 2.1x=x+5.6 2.1x-x=x+5.6-x 1.1x=5.6 x=5.6/1.1 x=56/11 2011-08-26 16:44:27 補充： Q 8 : c/4+c/2= -1 A 8 : c/4+c/2= -1 4(c/4+c/2) = 4×-1 c+2c=-4 3c=-4 3c/3=-4/3 c = -4/3 2011-08-26 16:44:32 補充： Q 9 : Solve the equation 2e+1/3=e-2/4 A 9 : 2e+1/3=e-2/4 2e+4/12-4/12=e-6/12-4/12 2e=e-10/12 2e-e=e-5/6-e e = -5/6
其他解答:
no.1 should be 0km/h....
留言列表
