Please help me 7th grade math operations with rational numbers

Mathematics

1 answer:

Katena32 [7]3 years ago

5 0

1. Stock Market:
If a stock price decreased $2 per day for four days, then the total change in value of the stock is $8. (2 x 4)
Answer: $8.

2. Evaporation:
With the given information, we can infer that if 3 inches of water in a tank decreases each week, then 15 inches of water would decrease over the course of 5 weeks. (3 x 5)
Answer: 15 inches.

3. Football:
If a football team lost 9 yards on 3 consecutive plays, then the team's total change in position is 27 yards. (9 x 3)
Answer: 27 yards.

Hope this helps! Good luck.

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Write down the quadratic equation whose roots are $x = -7$ and $x = 1,$ and the coefficient of $x^2$ is 1. Enter your answer in

pav-90 [236]

<h2>Steps:</h2>

So firstly, since we know that the coefficient of x² is 1, this means that this is our base equation:

y = x² + bx + c

Now, since we know that the roots are -7 and 1, set y = 0 and set x = -7 and 1 and simplify:

$0=(-7)^2+b(-7)+c\\0=49-7b+c\\-49=-7b+c\\\\0=1^2+b(1)+c\\0=1+b+c\\-1=b+c\\\\-49=-7b+c\\-1=b+c$

Now with this, we can set up a system of equations to solve for b and c. For this, I will be using the elimination method. For this, subtract the 2 equations:

$\begin{alignedat}{2}-49&=-7b+c\\-(-1&=b+c)\\-48&=-8b\end{alignedat}$