Math Is Fun Forum

the_white_sheep

Member

Registered: 2005-09-05

Posts: 9

Simplify, expand and evaluate.....Please check and help

Hi

Please could you check the following as I want to see if my workings are correct:

Please help by showing me your working out:

Thanks alot;

1) Simplify:

a) X^2 x X^4 (I thinks its X^6?)

b) 2(3a + b) - (a - 2b) = (is it this, 6a + 2b - a - 2b = 5a (correct?)

2) Expand:

a) (a + b) (a - b)

b) (a + b) (b + c) (c + d)

3) Evaluate z when:

a) z = __________
        /  x + y
       /__________  and x = 5, y = 3
    \/     x + y

b) 1 - z = 4z - 9

c) z - 1        2z + 3
_______ =________
   
   z + 3        2z - 3

I really appreciate your kind help, please help by showing your working as I want to learn maths really well so badly!

Thank you!

Flowers4Carlos

Member

Registered: 2005-08-25

Posts: 106

Re: Simplify, expand and evaluate.....Please check and help

hi yaz white sheep!!!!

1a) yes ur right!!!  hooray for you!!!!!

1b) awwww..... u missed it by one mistake.  use the properties of multiplication by negatives:
           -1(-1)=+1          -1(1)=-1           -(a-b)=-a+b
      try and finish the problem knowing the above.

2a) (a+b)(a-b)
      = a(a) + a(-b) + b(a) + b(-b)
      = a² -ab + ab -b²
      = a² - b²

2b) (a+b)(b+c)(c+d)
      = (ab + ac + b² + bc)(c+d)
      = abc + abd + ac² + acd + b²c + b²d + bc² + bcd

3a) i will let u solve this one.  use the following properties:
             a/a = 1      the a's cancel out   

            (a-b)/(a-b) = 1    same thing here

3b) 1 - z = 4z - 9
      step 1) tranfer all of the z's onto one side:
                 1 -z + z = 4z + z - 9
                 1 = 4z + z - 9
                 1 = 5z - 9
           (remember: if you want to move something to the other side you must do the opposite of it's         
            sign to both sides)

        step 2) move all of the constants to the other side and solve for z:
                 1 + 9 = 5z - 9 + 9
                 10 = 5z
                 (10)/5 = (5z)/5
                   2 = z

2d)    (z-1)/(z+3) = (2z+3)/(2z-3)
                 
        use the following property:
           a/b = c/d
           a(d) = c(b)
           
          (z-1)(2z-3) = (2z+3)(z+3)

try and work out the last one.  if you run into trouble you know where to get help!!

c yaz!

Last edited by Flowers4Carlos (2005-10-14 07:08:24)

the_white_sheep

Member

Registered: 2005-09-05

Posts: 9

Re: Simplify, expand and evaluate.....Please check and help

Thanks alot you guy's are great!