X2 -4x -165 = 0

must show that you have checked your answer by substituting the values obtained into the original expression

show each step of the solution,

Thanks

- March 31st 2010, 01:18 AMJay1001Quadratic equation by factorisation (without using the standard formula)?
**X2 -4x -165 = 0**

**must show that you have checked your answer by substituting the values obtained into the original expression**

show each step of the solution,

Thanks - March 31st 2010, 01:44 AMwatto23
The equation can be factorized by inspection. The two numbers in the brackets must multiply together to make -165, so.....

If you find all the prime factors of 165, they are 3, 5, and 11. and note that 3x5 = 15

You also know that the sum of the two numbers in the brackets must be -4.

and.....

11x-15=-165

11+(-15)=-4

x^2-4x-165 = (x+11)(x-15) - March 31st 2010, 02:46 AMJay1001
(Nod)this may sound like a silly question but am new on here, what does this symbol represent (^), thanks for your help mate. is your answer to my question the fully solved answer??

- March 31st 2010, 02:51 AMwatto23
yer mate thats the answer. The ^ means 'to the power of'

so x^2 is x squared

and x^3 is x cubed etc. - March 31st 2010, 02:59 AMJay1001
Cheers mate

- March 31st 2010, 03:03 AMJay1001
one more question mate, bit cheeky of me i know sorry.(Wink)

Solve the following quadratic equation by implementing the formula method.

Answer to 3 significant figures

Can you Show each step to the solution please.

5x2 + 5x – 4x2 + 2x= 20

The standard form of the quadratic equation is

Ax2 + bx + c = 0

How would this be solved??

- March 31st 2010, 05:09 AMamul28
5x2 + 5x – 4x2 + 2x= 20

take x terms together n x^2 trems together

so u get

x^2+7x-20=0

u cannot factorise thie equation

if d equation is ax^2+bx+c=0

so use (-b+sq(b^2-4ac))/2a n (-b-sq(b^2-4ac))/2a

these two r the values of x

i guess u know this(Thinking)