# Math Help - Some of my math lab problems?

1. ## Some of my math lab problems?

1, 7(x-x2 ) +4(x2-2x)

2, 3+2x- 2/5(10x -3)

3, -2(x2 +7x-5)

4, 2/3(x-1/3) - (x+2)

5, 2x-12 for x =-3

6, x/2+3x for X=-2

7, x/2 + 3x for x=2/5

8, 2z2-z+1 for z=-1/2

9, z-z2 for z=-2/3

10, -x3 + 7x for x=1/5

Thank you to anyone who is willing to help me with these

2. Originally Posted by Kevin19
1, 7(x-x2 ) +4(x2-2x)
In this type of question you have to expand the brackets, The number outside is multiplied through each term inside.

$7(x-x^2 ) +4(x^2-2x)$

$7\times x-7\times x^2 +4\times x^2-4\times 2x$

$7x-7x^2 +4x^2-8x$

Now you must group any like terms.

$-3x^2 -x$

Originally Posted by Kevin19

5, 2x-12 for x =-3
This time replace x with -3

$2x-12$

$2(-3)-12$

$-6-12$

$-18$