Transcript Solving Equations! {with decimals}

U2L11
PS2 Solve single- and multi-step word problems
involving operations with fractions and decimals
and verify the solutions
SOLVING EQUATIONS! {WITH DECIMALS}
DO NOW:
JJ is baking a cake. He wants to
double the recipe so he has enough
to share with the whole class.
The recipe calls for 3 ½ cups of
flour. First he added 1 ¾ cup and
later he added 2 ½ cups. How
many more cups of flour does he
need?
Planner:
Hw p. 216 217 #9, 22, 23,
38, 40, 41
WHAT IS AN EQUATION?

Equation: a mathematical statement that two
things are equal.
It consists of two expressions, one on each side of an
'equals' sign.
 We know the left side and right side are equal

Equations
are like a
balance scale
SOLVING AN EQUATION -- TERMINOLOGY
“Solving the equation” = The process of
finding the value of the variables
 We say "solve for x" - meaning solve the
equation to find the value of the unknown
number x that makes the statement true


In order to “solve for x”, we must “isolate the
variable”
(We need to get x alone on one side of the equal
sign)
 Goal is to end up with x = something

HOW TO SOLVE EQUATIONS

To get x alone– UNDO every operation that is
happening to x
UNDO  perform the opposite operation
 Do PEMDAS in reverse! (add/subtract first, then
multiply/divide, etc)


Whatever you do to an equation,
do the S A M E thing
to B O T H sides of that equation!


Keep the scale balanced
Example:
x + 4.5 = 23.2
-4.5 -4.5
x = 18.7
•4.5 is being added to x, so we UNDO the
operation by doing the opposite operation
•Subtract 4.5 from BOTH SIDES
•If I have x = something, I’m done
ANOTHER EXAMPLE
2x – 12.4 = 32.4
+12.4 +12.4
2x
2
= 44.8
2
x = 22.4
•12.4 is being subtracted
from x, so we UNDO it by
ADDING 12.4 to both sides
•We don’t quite have x =
something so we have
more work to do
•X is being multiplied by 2,
so we UNDO it by
DIVIDING both sides by 2
•X = something, we are
done!
I CAN SOLVE EQUATIONS…

"You gotta do the same thing on both sides“
Examples:
 p + 8 = 14.1
 n + 4.7 = −4.7

x = −7
 1.2
 n + 3.9 = 0.7
 −6.3n = −8.19
 32.663 = p + 11.363
ASSIGNMENT

P. 216- 217 #9, 22, 23, 38, 40, 41