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secondary 2 | Maths
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I need help with question 11.
Please help (with reasons)
Thanku!!!
Date Posted: 5 years ago
Views: 254
This is a relatively easy question to understand
For the distance for whole journey:
Dist= speed × time
Total Dist
=(X +1)(X) + (2X+5)(X-1)
= X^2 + X + (2X^2 + 3X -5)
= 3X^2 + 4X -5
i)And since whole journey is 90km
3X^2 + 4X -5 =90
3X^2 + 4X -95=0 (shown)
ii) To solve this you have to use the quadratic equation formula and you will get X=5 and X=-6.333(rej as Dist is a pos no)
iii) Time Taken for whole journey
= X + X-1
= 5 +5-1
=9 hours
For the distance for whole journey:
Dist= speed × time
Total Dist
=(X +1)(X) + (2X+5)(X-1)
= X^2 + X + (2X^2 + 3X -5)
= 3X^2 + 4X -5
i)And since whole journey is 90km
3X^2 + 4X -5 =90
3X^2 + 4X -95=0 (shown)
ii) To solve this you have to use the quadratic equation formula and you will get X=5 and X=-6.333(rej as Dist is a pos no)
iii) Time Taken for whole journey
= X + X-1
= 5 +5-1
=9 hours
See 1 Answer
done
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Follow my writing in red, not black.
This question hinges on the formula "Distance = Speed x Time".
You need to find the total distance walked in terms of x, the total distance cycled in terms of x and then sum them up to find the total distance.
Here, the total walking distance is x (x + 1) km. The total cycling distance is (x - 1) (2x + 5) km. Altogether, the distance for the journey is x (x + 1) + (x - 1) (2x + 5) km.
Since we are given that the numerical value for this total journey distance is 90 km, we need to equate our algebraic expression to 90.
We then need to expand the brackets and simplify the terms until you obtain the quadratic expression needed.
From there, you should do cross factorisation to obtain two values of x.
One of the values of x is negative and it has to be rejected, since x represents time which must be positive.
The total time is simply x + x - 1 = 2x - 1 and we need to substitute the positive value of x into this 2x - 1 to obtain our answer.
This question hinges on the formula "Distance = Speed x Time".
You need to find the total distance walked in terms of x, the total distance cycled in terms of x and then sum them up to find the total distance.
Here, the total walking distance is x (x + 1) km. The total cycling distance is (x - 1) (2x + 5) km. Altogether, the distance for the journey is x (x + 1) + (x - 1) (2x + 5) km.
Since we are given that the numerical value for this total journey distance is 90 km, we need to equate our algebraic expression to 90.
We then need to expand the brackets and simplify the terms until you obtain the quadratic expression needed.
From there, you should do cross factorisation to obtain two values of x.
One of the values of x is negative and it has to be rejected, since x represents time which must be positive.
The total time is simply x + x - 1 = 2x - 1 and we need to substitute the positive value of x into this 2x - 1 to obtain our answer.
Date Posted:
5 years ago
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