Algebra help! A question I'm really struggling with?

Question

Algebra help! A question I'm really struggling with?

Answer 1

All you have to do to multiply the 3xy is just multiply them all together. 3 times -2 equals -6. And -6 times 5 is -30. So the first part of your problem is -30.



However there is one thing you did wrong in the second part of the problem. When dealing with exponents (the ^2), you absolutely HAVE to do the exponent before everything else. So instead of 15^2, it's actually y^2 and THEN multiply it by 3.

So your result for the second half of the problem is actually 75.



Therefore, your result is 45. :)

Answer 2

3*x*y+3*y^2.

(3*-2*5)=-30 and 3*5^2=3*25=75.

So 75-30=45.

Answer 3

Okay Anna, lets tackle your imediate problem first.

What does 3xy mean?

Well, although they haven't been written in , it just means 3 times x times y. The multiplication signs are understood to be there.



The other term is read as 3 times y(squared)



You have been given that

x = -2 and y = 5



So, just substitute these values into the expression you started with, giving



( 3 * (-2) * 5) + ( 3 * 5^2) = - 30 + 75 = 45



Remember, minus signs were invented by the god of maths to torment the human race [especialy youngsters!!] So be very careful with them!! More silly mistakes are made with minus signs than any other sign used in maths!! Even after 55 years, they can still work their evil on me!!

Answer 4

3 * x * y = 3 * -2 * 5 = -30



Is the minus tripping you up? If so there are two tricks you can use:



1. put the negative number inside parentheses like (-2). This lets your eye see it as a number and not as a subtraction.



2. Put the minus above the number like this:

_

8 = 2 = 10



This is not so far fetched as you might think. It is a common trick used in, for example, crystallography and in the programming language APL (actually APL just pushes the negative to the top of the line in front of the number and calls it "high minus")

_

8 - 3 = 5

Answer 5

3xy+3y^2 is an expression.

(It would have to have an equals sign to be an equation)

It means

3 * x * y + 3 * y * y



Whenever x is written replace it by -2

Whenever y is written replace it by +5



So now you have

3 * (-2) * 5 + 3 * 5 * 5 = -30 + 75 = 45



I hope that seems clearer



Regards - Ian

Answer 6

ok.

step 1 : replace each x with (-2) and each y with 5



step two : wite the equation

3(-2)(5)+3(5)^2



step three : follow the order of operations precedence

power > multiply(or division) > addition(or subtraction)



step four : perform operations with the right order of precedence

power ----> 3(-2)(5)+3(25) ----------------------> 5^(2) = 25

multiply---> 3 * -2 = -6 and -6 * 5 = -30 and 3 * 25 = 75 so the equation becomes

-30 + 75

addition---> -30 + 75

or

+75 - 30 = 45

done.

Answer 7

-Your mistake is that your are not following the "Order of Operations".

-Order of Operations: PEMDAS- Parenthesis, Exponents, Multiplication/Division, Addition/Subtration.



3xy + 3y^2, with x=-2 & y=5



3(-2)(5) + 3(5)^2 = -30 + 3(5)^2

-"NOTE: With 3(5)^2, according to the order of operations we must do the exponent (5)^2 before we mutiply"



Thus: -30 + 3(5)^2 = -30 + 3(25) = -30 + 75 = 45

Answer 8

All you need to do is plug in the x and y values in the equation.

3xy + 3y^2

3(-2)(5) + 3(5)^2

First just multiply the first 3 numbers...

-6(5)

-30 + 3(5)^2

Now you need to solve 5^2 because it comes first in the order of operations.

5^2 = 25

-30 + 3(25)

-30 + 75

45 is your answer.

Enjoy.

Answer 9

All you have to do is replace the variables with the value.



3xy+3y^2

x= -2 y=5



3X -2X5+ 3X5^2

1. Do the exponent first

5^2= 25

3X -2X5+ 3X25

2. Multiple 3 and -2

3X -2= -6

-6X5+3X25

3. Multiple -6 and 5

-6X5= -30

-30+ 3X25

4. Multiple 3 and 25

3X25= 75

-30 +75

5. Add

45 is the answer





Remember PEMDAS

Parenthesis, Exponent, Multiply or Divide, Add or Subtract

Answer 10

3xy = 3 times -2 times 5.

3 times -2 = -6,

then -6 times 5 = -30



3y^2 = 3 times (5 squared) = 3 times 25 = 75.

The exponent (2) in 3 y^2 only applies to y; not to 3y. If it applied to 3y, it should be written "(3y)^2 = 15^2.



I hope that this helps.

Answer 11

I am not exactly sure what you mean by the question but when I multiplied 3xy I got -30. Hope this helps some.

Answer 12

45

Answer 13

You are on the right track, you understand what you need to do is substitution... so...



(3)*(-2)*(5)+(3)(5^2)



it should be obvious that the first number is going to turn negative for proof, what is:

(-1)*(2)? -2