please help me answer these questions as much as you can?

Question

please help me answer these questions as much as you can.

1. what is the √128?

2. 3√5(√20)=30

3. √27+√75

4. Solve: 5(7x+3)

5. (6+5√3)(6-5√3)

6. √7(5+√7)

7. 7m(m-6)

please number them so that I can know what answer is to what number.

thank you.

Answer 1

1 8√2
2 ??
3 15√3
4 35x+15
5 -39
6 5√7+7
7 7m^2-42m

Answer 2

1. √128 = √(64 * 2) = √64 * √2 = 8√2

2. 3√5(√20) = 3 * √(5 * 20) = 3 * √100 = 30

3. √27+√75 = √(9 * 3) + √(25 * 3)
= √9 * √3 + √25 * √3
= 3√3 + 5√3 = 8√3

4. 5(7x+3) = 35x + 15

5. (6+5√3)(6-5√3)
Use FOIL
= 36 - 75 = -39

6. √7(5+√7) = 5√7 + 7

7. 7m(m-6) = 7m^2 - 42m

Leave the answers in radical form, as I have done. Do not approximate them with rational numbers as BiteMe has done. Number 2 is exactly 30. No rounding is involved, unless you incorrectly use your calculator to convert everything to rational numbers first. The problem here is to manipulate radicals, not convert them to rational approximations.

Answer 3

I'll just pick one at random, to show you how, then you do the rest.

2. 3 √5√20 = 30

= 3 (√5√20)=30
= 3 (√5(20) )=30
= 3 (√100)=30
= 3(10)=30
= 30 = 30


Multiply the radicals first, then evaluate them

Answer 4

dont you have a calculator on your computer or cant you buy one.
1. 11.3137
2. 3X2.2360(4.4721)=30 4 decimal no rounding
3. 5.1961+8.6602=13.8564
.........