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3 years ago

Y=-x+7

Mathematics

1 answer:

Allisa [31]3 years ago

6 0

Question 1:
y=-x+7
y=2x-2

(-x+7)=2x-2
-x+7+x=2x-2+x
7=2x-2+x
7+2=2x-2+x+2
9=3x
9/3=3x/3
3=x

y=-x+7
y=-(3)+7
y=4

Question 2:
y-1=2x
y+2x=5

y-1=2x
y-1+1=2x+1
y=2x

(2x+1)+2x=5
2x+1+2x=5
4x+1=5
4x+1-1=5-1
4x=4
4x/4=4/4
x=1

y-1=2(1)
y-1+1=2+1
y=3

Answer: x=1 y=3

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Answer:

The step 4 is not what he should have done. But the wrong is step 5, because if he added -2x both sides, it would give the following equation:

$x-12=-4x+6$

and not $x-12=6$

Note that in step 4 he should have added 2x and not -2x to both sides, but we still have the equality. The problem is that step 5 is totally wrong.

I don't know what answer is expected to this question, but I would mark step 5, because this is mathematically wrong.

Solving the equation

$3(x-4)=-4-2(x-5)$

Using distribution

$3x-12=-4-2x+10\\3x-12=-2+6$

Add $2x$ both sides

$3x-12+2x=-2x+6+2x$

$5x-12=6$

Add 12 both sides

$5x-12+12=6+12\\5x=18$

Divide both sides by 5

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

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3 years ago

Factorize x^2 - 5x +4 <br> i will mark brainliest if correct

noname [10]

Answer:

(x-1)(x-4)

Step-by-step explanation:

factors of four that add up to negative five

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3 years ago

Read 2 more answers

You have a wire that is 20 cm long. You wish to cut it into two pieces. One piece will be bent into the shape of a square. The o

Aleksandr [31]

Answer:

Therefore the circumference of the circle is $=\frac{20\pi}{4+\pi}$

Step-by-step explanation:

Let the side of the square be s

and the radius of the circle be r

The perimeter of the square is = 4s

The circumference of the circle is =2πr

Given that the length of the wire is 20 cm.

According to the problem,

4s + 2πr =20

⇒2s+πr =10

$\Rightarrow s=\frac{10-\pi r}{2}$

The area of the circle is = πr²

The area of the square is = s²

A represent the total area of the square and circle.

A=πr²+s²

Putting the value of s

$A=\pi r^2+ (\frac{10-\pi r}{2})^2$

$\Rightarrow A= \pi r^2+(\frac{10}{2})^2-2.\frac{10}{2}.\frac{\pi r}{2}+ (\frac{\pi r}{2})^2$

$\Rightarrow A=\pi r^2 +25-5 \pi r +\frac{\pi^2r^2}{4}$

$\Rightarrow A=\pi r^2\frac{4+\pi}{4} -5\pi r +25$

For maximum or minimum $\frac{dA}{dr}=0$

Differentiating with respect to r

$\frac{dA}{dr}= \frac{2\pi r(4+\pi)}{4} -5\pi$

Again differentiating with respect to r

$\frac{d^2A}{dr^2}=\frac{2\pi (4+\pi)}{4}$ > 0

For maximum or minimum

$\frac{dA}{dr}=0$

$\Rightarrow \frac{2\pi r(4+\pi)}{4} -5\pi=0$

$\Rightarrow r = \frac{10\pi }{\pi(4+\pi)}$

$\Rightarrow r=\frac{10}{4+\pi}$

$\frac{d^2A}{dr^2}|_{ r=\frac{10}{4+\pi}}=\frac{2\pi (4+\pi)}{4}>0$

Therefore at $r=\frac{10}{4+\pi}$ , A is minimum.

Therefore the circumference of the circle is

$=2 \pi \frac{10}{4+\pi}$

$=\frac{20\pi}{4+\pi}$

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Answer:

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Answer:

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Step-by-step explanation:

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