3 years ago

Solve each equation mentally

Mathematics

1 answer:

Phoenix [80]3 years ago

5 0

1. x=2
2. X=100
3. X=100
4.-1

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-5x+y=-3

serg [7]

(3)(-5x+y=-3)
(5)(3x-8y=24)

-15x+3y=-9
15x-40y=120

3y=-9
-40y=120

-37y=111
Divide both sides by -37

y=-3

To solve for x. Choose one equation from the given and plug what you get in Y.

I'll choose, -5x+y=-3
So, -5x+(-3)=-3
-5x=0
Divide both sides by -5
x=0/-5

Hope, this helps.

5 0

3 years ago

4 - 5/2 * (1/10x) = 1 what is the value of x

Inga [223]

$4 - 5 / 2 * (1/10x) = 1\\$

The first step is to identify the order in which the equation must be solved, by following PEMDAS (you might know it as BEDMAS):

Parenthesis (or Brackets)

Exponents

Multiplication and Division

Addition and Subtraction

My advice would be to add parenthesis, following these rules, if you are not very good at finding them immediately by sight.

So:

$4 - 5 / 2 * (\frac{1}{10x}) = 1\\\\4 - [(5/2)*(\frac{1}{10x})]=1\\\\4-(2.5*\frac{1}{10x})=1\\\\4-\frac{2.5}{10x}-1=0\\3-\frac{x}{4}=0\\\frac{x}{4}=3\\x=3*4\\x=12$

We check our answer:

$x=12\\4 - [(5 / 2) * (1/10)*(x)] = 1\\4 - [(5 / 2) * (\frac{1}{10}) * (12))] = 1\\4 - [2.5 * (\frac{1}{10})*12] = 1\\4 - [(\frac{2.5}{10})*12] = 1\\4 - [(\frac{1}{4})*12] = 1\\4 - 3 = 1\\1=1$