Math homework!!! How do you solve 3x = 15...?

There pretty easy but here's a step by step of how to do them. Hope it helps!

REMEMBER TO STAY CALM!ALL YOU'RE TRYING TO DO IS TO ISOLATE THE VARIABLE.

1.

(3x)/3=15/3

x=5

Divide by 3 on BOTH Sides. DO the inverse operation .Division is the opposite of multiplication.

To Check=> ALWAYS Replace the value for X into the equation.

3(5)=15 / Both sides of the equation are the same so the

15=15 \/ equation is true.

2.

x/9 = -2

| | |

V V V

_9_ . _x_ = _9x_= x = (-2)(9) = 18

1 9 9 | | |

V V V

x = -18

Multiply by 9 on Both sides. Do the inverse oporation. Multiplication is the opposite of division.

Check :

-18/9=-2 / Both sides of the equation are the same so the

-2=-2 \/ equation is equal.

3.

_-b _= _12.5_

-1 -1

b= -12.5

Divide by 1 because there is an invisible 1 in front of the b. SO it's -1 . So the queation is saying -1 times b is 12.5.

Check:

-1(.12.5)=12.5 / Both side of the equation are equal so the

12.5=12.5 \/ equation is true!

Yo have to try to solve the problem by solving for one variable at a time. For this problem I would multiply x+2y=5 by -3, which would make the problem -3x-6y=-15. Now add the 3x+7y=18 to this and the x will cancel out leaving you with y=3. Now plug in the #3 in one of the equations and solve for x. 3x+7(3)=18 which is 3x+21=18. Subtract 21 from both sides which leaves you with 3x=-3. Divide both sides by 3 which will give x=-1. Now check by plugging -1 into x and 3 into y, such as -1+2(3)=5 which is -1+6=5, which is 5=5. That's correct! Hope it makes sense.

well this is just algebra. for any algebra problem u just do the opposite of the symbol on both sides of the equal sign so like for 3x= 15 u would divide the side with the 3x by 3, and then divide the other side (15) by 3. then to check ur work u would just plug the number u got (when you divided 15 by 3) into the x makingg it 3(whatever number u got) = 15. u should get 5 for tht one. if its like x/9=-2 then u multiply both sides by 9.

for -b= 12.5 switch the signs on both sides so the problem would say b = -12.5...

1.) 3x = 15

For multiplication problems like this, you use division. Divide the answer (15) by the other number in the problem (3) and it will give you the value of "x".

2.) x/9 = -2

For division problems like this one, you use multiplication. So you take the answer (-2) and multiply it by the devisor (9) and you will get the answer for the value of "x" (the dividend).

Since the answer to the problem is a negative number, that means that the dividend will also be a negative. Two negatives in multiplication will cancel each other out, but a negative number multiplied by a positive will result in a negative number.

3.) -b = 12.5

I wish that I could help you out on this one, but I don't remember how to solve something like this. Sorry.

While resolving these kind of equations, you always want to try to isolate x (or a or b) on one side of the equation.

To do that, you can add, substract, multiply or divide BOTH sides of the equation by whatever you want.

So for the first one, you want to divide both sides by 3 so you can have an x on its own on one side. That gives you the value of x.

Same thing fo 2), you multiply both sides by 9 to get rid of the fraction (because 9 times x/9 equals x).

And for 3) you already have an isolated b, but its negative. So what you have to do is multiply by -1 to get the value of b.

1) divide both sides of the equation by 3:

3x/3 = 15/3

x = 5

2) multiply both sides by 9:

9x/9 = -2 x 9

x = -18

3) divide both side by -1 or multiply both sides by -1 or just switch the signs round.

if -b = 12.5 then b = -12.5

hope this helped =)

1. X= 15/3

X= 5

2. X=-2x9

X= -18

3. B=absolute value of 12.5

B= 12.5

stay calm.

1) 3x=15

you want to isolate the x, and to do that, you divide by 3 on both sides of the equal sign.

3x/3=15/3

the two 3s on the left side cancel out to leave x, and 15/3 is 5.

x=5

2) x/9=-2

to isolate this x, you multiply both sides by 9.

9x/9=-2*9

the two 9's cancel out on the left side, and on the right side -2*9 is -18

x=-18

3) -b=12.5

-b is the same thing as -1*b

to cancel this out, we can divide by -1 on both sides to make b positive

-b/-1=12.5/-1

b=-12.5

good luck with the rest of the problems!

3x = 15... 3x means 3 times 'x' is equal to 15.

15 / 3 = x Divide...

So, 5 = x

Than check it,

3 x 5 = 15...

1) divide both sides by 3

2) multiply both sides by 9

3) multiply (or divide) both sides by -1

basic instruction is to do the opposite function of whatever you want to cancel out