## anonymous one year ago If (8z − 9)(8z + 9) = az2 − b, what is the value of a? The value of a is ____________.

1. anonymous

Im pretty sure its 8 but i want to be sure

2. welshfella

what did you get for the expansion of (8x - 9)(8z + 9)?

3. nincompoop

it is distributive property the coefficients are multiplied $$(ax+b) (ax-c) = (ax \times ax) - (ax \times c) + (ax \times c) - (b\times c)$$ if you focused on a, it will be $$a \times a = a^2$$

4. anonymous

i dont understand

5. anonymous

how you got that

6. nincompoop

I am providing the general idea without answering your own homework.

7. princeharryyy

multiply the left hand side and compare the coefficients according to the power of z

8. nincompoop

the coefficients in the first parenthesis will have to be multiplied to the coefficient in the second parenthesis

9. princeharryyy

@lealealea222

10. anonymous

this question confuses me so bad, i dont understand what your saying, im sorry

11. nincompoop

what is a multiplied by a ?

12. anonymous

2?

13. nincompoop

let us use an actual number $$2 \times 2 = ?$$

14. anonymous

4

15. nincompoop

$$4 \times 4 = ?$$

16. anonymous

WAIT its ^2 im so sorry

17. anonymous

its az^2 − b

18. nincompoop

but you are not worried about z nor b you have to worry about a

19. anonymous

ok ok, 8

20. anonymous

no 16

21. nincompoop

how about $$8 \times 8 = ?$$

22. anonymous

64

23. nincompoop

did you notice that $$2 \times 2 = 2^2$$ $$4 \times 4 = 4^2$$ $$8 \times 8 = 8^2$$

24. anonymous

yes

25. anonymous

so its 64??

26. nincompoop

yes, because the coefficient are both 8

27. nincompoop

if the coefficients were different then you will multiply them as well

28. anonymous

Thankyou :)

29. anonymous

can you help with one more?

30. nincompoop

maybe post it

31. anonymous

Consider the functions f(x) = 2x + 1 and g(x) = x2 − 10. What is the value of f[g(3)]? 39 −3 −7 -1

32. anonymous

its like the other one but i dont know it

33. anonymous

@nincompoop