(請用substitution or elimination to solve the simultaneous equation!!)
16.the sum of the digits of a 2-digit number is12.if the two digits are reversed,the value of the number is decreased by 36.find the original number.
(Answer 84)
17.in a 2-digit number,the tens digit is 5 more than the units digit.find the 2-digit
number if it is equal to the product of the units digit and 36.
(Answer 72)
18 .in a 2-digit number ,the ten digit is 2 more than the units digit.if the 2-digit
number is divided bu the sum of the 2 digits,the quotient is7.Find the original
2-digit number
(Answer 42)
19.there is a square and an equilateral triangle,their perimeter is the same.
(the length of the square is (2x+y-2)cm
the width底 of the equilateral triangle is (x+2y+11)cm:三角形的邊是(2x+y+1)cm
)
(a)the value of "x" and "y''
(Answer X=7,y= - 3)
(b)the area of the square
(Answer 81 cm^3)
26.the following table shows Billy's mobile phone service charges.
the charge of the voice connection is $0.6 per minute
the charge of the video connection is $0.8 per minute
(a)last month,Billy's mobile phone charge was $400.thi month ,his usage of
voice connection drcreased by 40% and his usage of video connection incresed
by 20%.AS a result ,his mobile phone charge decreased by 16% this month.
Find the actual usage of video and voice connection this month.
(Answer Video=240min:voice=240min)
更新1:
sorry!!可可可以做多兩條challenging question? 46.the solution of the simultaneous equation x+y=4x-y=5 is x=2,y=3. (b) Hence solve the simultaneous equation 1/a+1/b=4/a-1/b=5 (answer,x=2,y=3) 54.give that 1/a-1/b=X/a-b and a/b+b/a=Y,Find Y in terms of X. (answer,Y=2-X) 萬份感謝!!!!!!!!