Question 230413: solve the given equation for the variable 9x-2(x+4)=-29
Answer by PRMath(133)   (Show Source):
You can put this solution on YOUR website! 9x-2(x+4)=-29
First, we have to follow the order of operations that tells us to do math in the following order:
PEMDAS, which stands for:
Parenthesis
Exponents
Multiply
Divide
Add
Subtract
Now we can't really do anything in the parenthesis but we CAN multiply, so, let's multiply first....
9x-2(x+4)=-29 original problem
9x - 2x - 8 = -29 We distributed the -2, multiplying -2 times x and then 4.
7x - 8 = -29 Do you see how we combined like terms? 9x - 2x = 7x
Now we have to put the "X" information on the left and the numbers on the right side of the equal sign. How do we isolate the 7x? Well, we are subtracting 8 on the left, so if we ADD 8 on the left, we will get rid of it all together, right?
HOWEVER - if we ADD 8 on the left side of the equal sign, we must ADD 8 on the right side of the equal sign. Therefore, we have the following:
7x - 8 = -29
7x = -29 + 8 We added 8 to both sides of the equation
7x = -21 Do you see how -29 + 8 = -21?
Now we have to isolate the "x". How do we do that? Well, we are multiplying 7 times x, so to isolate the "X", we should DIVIDE by 7 on the left side of the equal sign. If we divide 7 on the left, we need to do the same thing on the right side of the equation..........
7x = -21
x = -3 Do you see that -21 divided by 7 equals -3?
THEREFORE...... now we know that x = -3. Is this correct? Let's "plug" -3 into the x areas of the original equation. Ready?
9x-2(x+4)=-29
9(-3) - 2(-3 + 4) = -29
9(-3) -2(1) = -29
-27 - 2 = -29
-29 = -29 YAYYyyyyy it works! :-)
I hope this helps you.
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