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4 years ago

Solve the equation.

Mathematics

1 answer:

elena55 [62]4 years ago

4 0

Answer:

C: $x=-3$ or $x=4$

Step-by-step explanation:

To solve the equation $x^2-x-12=0$ we need to factor it

We are looking for two numbers that when multiplied give -12 and when added give -x

This means that when factored, the equation would be $(x-4)(x+3)=0$

Now we can set each of these equal to 0, which means that at

$x=-3$ and $x=4$ , the equation will equal 0

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19. The present age of brother and sister are in the ration 4:5 Before three years the ration of their age was 3:4. find their p

Lyrx [107]

Answer:

Sister = 15 years old

Brother = 12 years old

Step-by-step explanation:

Right now, if the brother is B years old and the sister is S years old, B = (4/5)S because the ratio from brother to sister is 4:5, so if one unit is X, B = 4X and S = 5X

Three years ago, the brother was B-3 years old and the sister was S-3 years old. Keeping one unit as X, we have

B = 3X

S = 4X

B-3 = (3/4)(S-3)

Therefore, we have a system of equations

B = (4/5)S

B-3 = (3/4)(S-3)

Substitute (4/5)S for B into the second equation to only have one variable

(4/5)S - 3 = (3/4)(S-3)

(4/5)S - 3 = (3/4)S - 9/4

add 3 to both sides and subtract (3/4)S from both sides to isolate the variable and its coefficient

(1/20)S = 3/4

multiply both sides by 20 to isolate the S

S = 15

B = (4/5)S = 12

5 0

3 years ago

Round to the nearest tenth<br> 18 is what percentage of 79

GenaCL600 [577]

79 multiply .18 and you’ll get your answr

6 0

4 years ago

Where does the parentheses go in 3+6 ×9+3 to made a total of 84

chubhunter [2.5K]

Answer:

Around the 3 + 6:-

(3 + 6) x 9 + 3

Step-by-step explanation:

(3 + 6) x 9 + 3

= 9 x 9 + 3

= 84.

4 0

3 years ago

Read 2 more answers

Movies at the rental store are $3.75 each. Snacks and drinks are $1.89 each. Round each amount to the nearest dollar to estimate

Troyanec [42]

The estimate the total cost to rent 3 movies and buy popcorn, a soda, and a candy bar is $18. option C

<h3>Total cost</h3>

This is the summation of all units cost of items or the results of adding all cost(fixed and variable)

Cost of movies = $3.75

= $4.00 to the nearest dollar

Cost of snacks (drinks, popcorn, candy bars) = $1.89 each

= $2.00 to the nearest dollar

Cost to rent 3 movies and buy popcorn, a soda, and a candy bar.

Total cost = (Cost of movies × number of movies) + cost of popcorn + cost of soda + cost of candy bar

= (4 × 3) + 2 + 2 + 2

= 12 + 2 + 2 + 2

= $18

Therefore, the estimate the total cost to rent 3 movies and buy popcorn, a soda, and a candy bar is $18. option C

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3 0

2 years ago

If 1116 parts were made in 7 hours how much parts were made an hour

vampirchik [111]

Hello! To solve this question, all you have to do is divide the total amount of parts made by the number of hours. 1116/7 is 159.42857 and other numbers, or 159 when rounded to the nearest whole number. There were about 159 parts made an hour.

8 0

3 years ago