Question

[Phùng Thiên Phước]

Giúp mình làm các câu hỏi này nha: (càng nhiều càng tốt!)

1. Tiffany and Ryan deposit some amount in a joint bank account such that total balance remains 500. If  amount deposited by Tiffany and Ryan are plotted as a linear graph on xy plane, find the area between this graph and the coordinate axis.

2.A group of workers is paving a road. If they pave 200m of the road a day, they will need 3 more days. to finish the work. If they pave 240m of the road a day, they will finish the work 2 days in advance. How long is the road, in meter?

3. Mrs. Darlie has a silver ring, a golden ring and a diamond ring. She put them on her left hand. Each ring can be on any of the five fingers. When there are two or three rings on the same finger, if the order in which they are put is different, that couunt as a different way. How many different ways for Lea to put these rings?

4. Let P(x) be a polynomial with degree 3 such that P(1)=3, P(2)=3, P(3)=7, P(4)=21. Find the value of P(5).

Answer 1

[ღ๖ۣۜLinh's ๖ۣۜLinh'sღ] ★we are one★]

4. Call that polynomial P (x) = ax³ + bx² + cx + d

We have P(1)=a+b+c+d=3   (1)

P(2)=8a+4b+2c+d=3   (2)

P(3)=27a+9b+3c+d  =7       (3) 

P(4)=64a+16b+4c+d     =21    (4)

From (1) and  (2) =>  7a+3b+c=0

From (1) and  (4)  => 63a+15b+3c=18

=> 12b+6c=-18  => 2b+c=-3

From (1) and  (3) =>26a+8b+2c=4=> 13a+4b+c=2

=> 13a+2b=5

It is possible