FIRST DEGREE EQUATIONS
BY GLORIA GRAZIOLIA QUESTION OF BALANCE….
IN THE EQUATION…
7 added to a number gives 15…
Solving the equation means, finding the value of the variable that makes the equation true.
Let’s go back to the balance!
x+7=15
SO THE SOLUTION GOES LIKE THIS…
SUBTRACT 7 FROM BOTH SIDES
x+7-7=15-7
SIMPLIFY BOTH BESIDES
x+7-7=8
NOW WE KNOW THE VALUE OF X
x=8
A BIRTHDAY’S PROBLEM
ANDREW IS TEN YEARS OLDER THAN HIS BROTHER. SIX YEARS FROM NOW HE WILL BE TWICE HIS BROTHER’S AGE THAN.
HOW OLD IS ANDREW NOW?
X BROTHER AGE
X+10 ANDREW AGE NOW
6 YEARS FROM NOW…
X+6 BROTHER AGE
(X+10)+6=X+16 ANDREW AGE
x+16=2(x+6) x+16=2x+12
16-12=2x-x
x=4
SOLVE EACH EQUATION
A) 2x + 2 = x + 9
B) 3x + 1 = x + 5
C) 6x – 8 = 4x
D) 5x + 1 = x - 11
x = 7
x = 2
x = 4
x = -3
IN YOUR EXERCISE BOOKS:
WRITE EACH EQUATION AND SOLVE IT TO FIND X .
A) 2 (x + 3) = x + 7 B) 5 (2x - 1) = 3x + 9 C) 2 (5x + 2 ) = 5x - 1 D) 3 (x – 1) = 2 (x + 1)
x = 1 x = 2 x = -1 x = 5
SOLVING A PROBLEM
A flowerbed is in the shape of a triangle with one side twice the length of the
shortest side, and the third side is 30 feet more than the length of the shortest side.
Find the dimensions if the perimeter is 102 feet.
Read and reread the problem. Recall that the formula for the perimeter of a triangle is 2p = a + b + c.
x = the length of the shortest side
2x = the length of the second side x + 30 = the length of the third side
in the formula 2p=a+b+c
substitute: 102 = x + 2x + x + 30 Solve:
102=4x+30 72=4x
x=18
