OK. These problems are easy if you know the quadratic formula,
and they're impossible if you don't.
Here's the quadratic formula:
When the equation is in the form of Ax² + Bx + C = 0
then x = [ -B plus or minus √(B²-4AC) ] / 2A
I'm sure that formula is in your text or your study notes,
right before these questions. You should cut it out or
copy it, and tape it inside the cover of your notebook.
Then, you'll always have it when you need it, until
you have it memorized and can rattle it off.
The first question says 3x² + 5x + 2 = 0
Is this in the form of Ax² + Bx + C = 0 ?
Yes ! A=3 B=5 C=2
so you can use the quadratic formula to solve it.
x = [ -B plus or minus √(B²-4AC) ] / 2A
= [ -5 plus or minus √(5² - 4·3·2) ] / 2·3
= [ -5 plus or minus √(25 - 24) ] / 6
= [ -5 plus or minus √1 ] / 6
x = -4 / 6 = -2/3
and
x = -6 / 6 = -1 .
_______________________________________
The second question says
4x² + 5x - 1 = 0
Is this in the form of Ax² + Bx + C = 0 ?
Yes it is ! A=4 B=5 C= -1
so you can use the quadratic formula to solve it.
x = [ -B plus or minus √(B²-4AC) ] / 2A
Now, you take it from here.
Go -6 for x axis and -4 for y axis
The giraffe (using the ruler) is 11 cm.
1 cm : 50 cm
Multiply both sides by 11.
11 cm : 550 cm
There are 0.01 meters in 1 centimeter.
Multiply 550 cm by 0.01.
(550)(0.01) = 5.5
The giraffe's real length is 5.5 meters.
Let the number be represented by x
2x=60+ 5x -20*2=60+5*-20
2x-5x=5x-5x+60 -40=60+-100
-3x=60 -40=-40
-3x/-3=60/-3
x=-20
Therefore the number is -20
Answer ; 10x - 20
Explanation; Multiply each term in the parenthesis by 10. Then multiply the numbers, and you get your answer.
