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3 years ago

Use the substitution method to solve these simultaneous equations.

Mathematics

1 answer:

Amanda [17]3 years ago

4 0

Answer:

Step-by-step explanation:

a) 3x+2(41-5x)=33 as y=41-5x is given

3x+82-10x=33

-7x+82=33

-7x=33-82

-7x=-49 cut the negative signs as its LHS and RHS

x=49/7=7

b)-5x+3(3x-3)=3 as y=3x-3 is given

-5x+9x-9=3

4x-9=3

4x=3+9

x=12/4=3

c)4x+11-5x=9

-x+11=9

-x=9-11

-x=-2 cut the negative signs as its LHS and RHS

x=2

d) 5y+ -5-2y=-11 as x=-5-2y is given

3y+-5=-11

3y=-11+5

3y=-6

y=-6/3=-2

e)-5x-4(2x+1)=35 as y=2x+1

-5x-8x+4=35

3x+4=35

3x=35-4

3x=31

x=31/3

x=10.3

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If you know that 4 of an item costs a certain amount, and you want to find out how much one costs, which operation will you use?

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Answer:

The answer would be division (B)

Step-by-step explanation:

4x equals the total amount

x equals the cost of one item

Therefore you'd divide total cost by 4 and that would find the cost of one item

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3 years ago

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URGENT WILL GIVE YOU 100 POINTS PLEASE ANSWER CORRECTLY

wariber [46]

Answer:

1. x = 18.4

2. x = -1.25

3. x = $\frac{5}{12}$

4. x = 12.3

5. x = 6.4

6. z = 5.8

7. x = $\frac{1}{12}$

8. x = - $\frac{1}{4}$

9. x = $\frac{1}{3}$

10. x = -9

11. z = 18

12. x = 7

13. x = -9

14. x = -36

15. x = -7

16. x = 8

17. z = -1.5

18. x = - $\frac{45}{7}$

19. x = 16

20. x = -12

21. x = $\frac{8}{3}$

22. x = -1.6

23. x = 1.8

24. x = -8.2

Step-by-step explanation:

1. x - 3.5 = 14.9 (add 3.5 to each side)

x = 18.4

2. x + 2.25 = 1 (subtract 2.25 from each side)

x = -1.25

3. - $\frac{1}{3}$ = x - $\frac{3}{4}$ (add $\frac{3}{4}$ to each side)

$\frac{3}{4}$ - $\frac{1}{3}$ = x (multiply $\frac{3}{4}$ by $\frac{3}{3}$ and $\frac{1}{3}$ by $\frac{4}{4}$ to get a common denominator)

$\frac{9}{12}$ - $\frac{4}{12}$ = x

$\frac{5}{12}$ = x

4. x - 2.8 = 9.5 (add 2.8 to each side)

x = 12.3

5. x - 8.5 = -2.1 (add 8.5 to each side)

x = 6.4

6. z - 9.4 = -3.6 (add 9.4 to each side)

z = 5.8

7. x + $\frac{5}{6}$ = $\frac{11}{12}$ (subtract $\frac{5}{6}$ from each side)

x = $\frac{11}{12}$ - $\frac{5}{6}$ (multiply $\frac{5}{6}$ by $\frac{2}{2}$ to get a common denominator)

x = $\frac{11}{12}$ - $\frac{10}{12}$

x = $\frac{1}{12}$

8. - $\frac{5}{6}$ + x = - $\frac{13}{12}$ (add $\frac{5}{6}$ to each side)

x = $\frac{5}{6}$ - $\frac{13}{12}$ (multiply $\frac{5}{6}$ by $\frac{2}{2}$ to get a common denominator)

x = $\frac{10}{12}$ - $\frac{13}{12}$

x = - $\frac{3}{12}$ = - $\frac{1}{4}$

9. x - $\frac{1}{9}$ = $\frac{5}{18}$ (add $\frac{1}{9}$ to each side)

x = $\frac{1}{9}$ + $\frac{5}{18}$ (multiply $\frac{1}{9}$ by $\frac{2}{2}$ to get a common denominator)

x = $\frac{2}{18}$ + $\frac{5}{18}$

x = $\frac{6}{18}$ = $\frac{3}{9}$ = $\frac{1}{3}$

10. x + 6 = -3 (subtract 6 from each side)

x = -9

11. z - 7 = 11 (add 7 to each side)

z = 18

12. -1 = x - 8 (add 8 to each side)

7 = x

13. -4x = 36 (divide each side by -4)

x = -9

14. - $\frac{x}{3}$ = 12 (multiply each side by -3)

x = -36

15. 63 = -9x (divide each side by -9)

-7 = x

16. 6.4 = 0.8x (divide each side by 0.8)

8 = x

17. -2.8z = 4.2 (divide each side by -2.8)

z = -1.5

18. - $\frac{7}{9}$ x = 5 (divide each side by - $\frac{7}{9}$ )

x = $\frac{5}{1}$ ÷ - $\frac{7}{9}$

x = $\frac{5}{1}$ (times) - $\frac{9}{7}$

x = - $\frac{45}{7}$

19. $\frac{1}{2}$ x = 8 (divide each side by $\frac{1}{2}$ )

x = 16

20. - $\frac{3}{4}$ x = 9 (divide each side by - $\frac{3}{4}$ )

x = -12

21. - $\frac{7}{8}$ x = - $\frac{21}{64}$ (divide each side by - $\frac{7}{8}$ )

x = - $\frac{7}{8}$ ÷ - $\frac{21}{64}$

x = - $\frac{7}{8}$ (times) - $\frac{64}{21}$

x = $\frac{448}{168}$ = $\frac{56}{21}$ = $\frac{8}{3}$

22. 1.6x = -3.2 (divide each side by 1.6)

x = -1.6

23. - $\frac{1}{2}$ = - $\frac{5}{18}$ x (divide each side by - $\frac{5}{18}$ )

1.8 = x

24. -2.5x = 20.5 (divide each side by -2.5)

x = -8.2

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Answer:

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