In a two-digit number, the units digit is greater than the tens digit by 3, and the sum of the spuares of the two digits is greater than the two-digit number by 3. Let the units digits be x.
(a) Express, in terms of x,
(i) the tens digit,
(ii) the value of the two-digit number.
(b) Hence find the two-digit number.
F.4 Math, 高手入, 急急急
2008-09-24 8:15 pm
回答 (1)
2008-09-24 8:28 pm
✔ 最佳答案
(a)(i) x-3
(ii) 10(x-3) + x
(b) ( x - 3 )^2 + x^2 = 10( x - 3 ) + x +3
x^2– 6x + 9 + x^2 = 10x - 30 + x + 3
2x^2 –17x + 36 = 0
( 2x – 9 )( x – 4 ) = 0
∴ x = 9/2 (rej.) or 4
The two-digit number is 14
收錄日期: 2021-04-13 16:06:21
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