Having problems these few algrebra problems?

Question

6. Multiply. Write the answer in scientific notation.
(2.4x10–5)(4 x10–4)

7. The diameter of the Milky Way disc is approximately 9 x 1020 meters. How long does it take light, traveling at 1016 m/year to travel across the diameter of the Milky Way?

8. Add 5y – 4 and 2y2 – 8y.

9. A triangle has sides 2x – 5, 3x + 1, and 4x + 2. Find the polynomial that represents its perimeter.

10. Remove the parentheses. –(3x + 5y)

Answer 1

** It would be clearer if you use the ^ sign to denote the power or the exponent. For example x^2 is the same as saying x squared.

In any case -

6) (2.4 x 10^-5)(4 x 10^-4)
= (2.4)(4) x (10^-5)(10^-4)
= 9.6 x 10^(-5 + -4)
=9.6 x 10^-9

7) If the diameter of the Milky Way disc is 9 x 1020, the total length is 9180 meters.

Travelling at a speed of 1016m/year,

Time = Length/Speed
= 9180/1016
= 9.035 years

8) 5y - 4 + 2y^2 - 8y
= 2y^2 + 5y - 8y - 4
= 2y^2 - 3y - 4

9) The perimeter of the triangle is the sum of the lengths of all three sides. Therefore,

Perimeter = (2x - 5) + (3x + 1) + (4x + 2)
= 2x + 3x + 4x - 5 + 1 + 2
= 9x - 2

10) -3x - 5y

Answer 2

(2.4 x 10 - 5)(4 x 10 - 4) =

(24 - 5)(40 - 4) =

(19)(36) =

684

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