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3 years ago

A student solved a system of equations by elimination. Describe and correct the error made in the part of the solution shown.

Mathematics

1 answer:

ivanzaharov [21]3 years ago

7 0

Answer:

x = -2; y = 3

Step-by-step explanation:

5x + 4y = 2 (1)

3x + 3y = 3 (2)

Multiply (1) by 3 and (2) by 4

15x + 12y = 6 (3)

12x + 12y = 12 (4)

Subtract (4) from (3)

15x - 12x = 6 - 12

3x = -6

x = -6/3

x = -2

Substitute x = -2 into (1)

5x + 4y = 2

5(-2) + 4y = 2

-10 + 4y = 2

4y = 2 +10

4y = 12

y = 12/4

y = 3

The first error is when he multiplied equation (2) by 4

He didn't multiply the right hand side of the equation by 4

3x + 3y = 3 ×4

12x + 12y = 12

But he wrote

12x + 12y = 3

The the next error is subtracting the left hand side of the equation and adding the right hand side

15x + 12y = 6

12x + 12y = 3

He wrote

3x = 9

Instead of 3x = 3

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Find the 20th term of the following sequence. -6, -4, -2, 0

posledela

Answer:

32.

Step-by-step explanation:

This is an arithmetic sequence with first term a1 = -6 and common difference 2.

an = a1 + d(n - 1)

a20 = -6 + 2(20-1) = 32

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3 years ago

If fx = 3x over 5 +3 which of the following is the inverse

Alborosie

Answer:

f^(-1)(x) = -3x/(3x-3)

Step-by-step explanation:

1) replace f(x) by y

● y = 3x/(5x+3)

2) exchange x and y

● y = 3x/(5x+3)

● x = 3y / (3y +3)

3) solve for y

● x = 3y / (3y +3)

● x (3y +3) = 3y

● 3xy + 3x = 3y

● 3xy - 3y = -3x

● y (3x - 3) = -3x

● y = -3x /(3x-3)

4) replace y with f^(-1)(x)

● y = -3x/(3x-3)

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3 0

3 years ago

A diagonal support beam is attached to the gate of a fence as shown. Which angles must be congruent in order for the top and bot

statuscvo [17]

Where is it shown? You need to attach a picture or something.

5 0

3 years ago

-1.2= y/2.4 -1.7 Solve for y

evablogger [386]

${\huge{\boxed{\sf{Question}}$

$-1.2= y\div2.4 -1.7$

Solve for y

${\huge{\boxed{\sf{Answer\:with\:explanation }}}$

let's put our equation first

$-1.2= y\div2.4 -1.7$

Flip the equation

$y\div2.4-1.7=-1.2$

Now follow the rule of $BOMDAS/PEMDAS$

${\huge{\boxed{\sf{BOMDAS }}}$

Brackets

Of multiplication

Division

Addition

Subtraction

${\huge{\boxed{\sf{PEMDAS}}}$

Parenthesis

Exponents

Multiplication

Division

Addition

Subtraction

_________________________

${\huge{\boxed{\sf{Solve\:the\:equation}}}$

_________________________

$y\div2.4-1.7=-1.2$

${\underline{simplify}}$

$0.416667y-1.7=-1.2$

add $1.7$ to both sides

$0.416667y=0.5$

Divide both sides by $0.416667$

$y=1.2$

${\huge{\boxed{\sf{Answer}}}$

$y$ would equal $1.2$

4 0

2 years ago

How many numbers greater than zero and less than 50 equal the product of two consecutive positive integers?

spin [16.1K]

Consecutive numbers would be like 2 and 3, or 7 and 8.

All we need to do is keep multiplying pairs of consecutive numbers until we get above 50.

1 × 2 = 2 (that's one.)
2 × 3 = 6 (two)
3 × 4 = 12 (three)
4 × 5 = 20 (four)
5 × 6 = 30 (five)
6 × 7 = 42 (six...)
7 × 8 = 56 > 50
We have a total of 6 numbers that equal the product of 2 consecutive intergers

7 0

3 years ago