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3 years ago

Simplify the expressioh 6.9-(-5)+4.1

1 answer:

6 0

This would be 16. When you subtract a negative number, it’s really like adding. Once this part is done, the expression would be 11.9+4.1. 11+4=15 and 0.9+0.1= 1. 15+1= 16.

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No work needed!! Just answers, thank you! 25 points!!

Maurinko [17]

Answer:

Step-by-step explanation:

$S_{31} = 9 \cdot 31 + [-0.5 \cdot \frac{31(31-1)}{2}] = 46.5$

$S_{40} = 40 + [-3 \cdot \frac{40(40-1)}{2}] = -2300$

3 0

2 years ago

What is the value of x?

Aliun [14]

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7 0

2 years ago

If f(x)=2x^2+3 then f(x-1)=2x^2+4x+5 <br> true or false

TEA [102]

Hello from Hello from MrBillDoesMath!

Answer:

False.

Discussion:

See attached file for discussion.

Thank you,

MrB

7 0

3 years ago

Solve for the compound inequality 6b < 42 or 4b + 12 > 8.

Anuta_ua [19.1K]

Answer:

-1<b<7, or i suppose b.

Step-by-step explanation:

6b<42

b<7

4b+12>8

4b>-4

b>-1

6 0

2 years ago

Need pre-cal help. Will mark best answer brainliest

OlgaM077 [116]

so, let's keep in mind that

$\bf \begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}$

so let's make a quick table of those solutions, say A, B, C solutions with x,y,z liters of acid, with an acidity of 0.25, 0.40 and 0.60 respectively.

$\bf \begin{array}{lcccl} &\stackrel{solution}{quantity}&\stackrel{\textit{\% of }}{amount}&\stackrel{\textit{liters of }}{amount}\\ \cline{2-4}&\\ A&x&0.25&0.25x\\ B&y&0.40&0.4y\\ C&z&0.60&0.6z\\ \cline{2-4}&\\ mixture&78&0.45&35.1 \end{array} \\\\\\ \begin{cases} x+y+z=78\\ 0.25x+0.4y+0.6z=35.1 \end{cases}$

we know she's using "z" liters and those are 3 times as much as "y" liters, so z = 3y.

$\bf \begin{cases} x+y+3y=78\\ x+4y=78\\[-0.5em] \hrulefill\\ 0.25x+0.4y+0.6(3y)=35.1\\ 0.25x+0.4y=1.8y=35.1\\ 0.25x+2.2y=35.1 \end{cases}\implies \begin{cases} x+4y=78\\\\ 0.25x+2.2y=35.1 \end{cases} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ x+4y=78\implies \boxed{x}=78-4y \\\\\\ \stackrel{\textit{using substitution on the 2nd equation}}{0.25\left( \boxed{78-4y} \right)+2.2y=35.1}\implies 19.5-y+2.2y=35.1$

$\bf 1.2y=15.6\implies y=\cfrac{15.6}{1.2}\implies \blacktriangleright y=13 \blacktriangleleft \\\\\\ x=78-4y\implies x=78-4(13)\implies \blacktriangleright x=26 \blacktriangleleft \\\\\\ z=3y\implies z=3(13)\implies \blacktriangleright z=39 \blacktriangleleft \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill \stackrel{25\%}{26}\qquad \stackrel{40\%}{13}\qquad \stackrel{60\%}{39}~\hfill$

5 0

2 years ago