help with simplfying this?

Question

2r(4r + 8) - 5r(6r - 10)

a. -22r^2 + 66r
b. 22r^2 + 66r
c. -38r^2 + 34r
d. -38r^2 + 66r

Answer 1

Multiply it out first:
8r^2 +16r -30r^2 +50r
Combine like terms
-22r^2 + 66r

The correct answer is a.

Answer 2

ok this is easy
first solve the 2r(4r+8) part. so you multiply 2r by 4r to get 8r^2 and then multiply 2r by 8 to get 16r.
so now the equation so far looks like this:
8r^2 + 16r - 5r(6r-10)
next solve the - 5r (6r-10) part. so take - 5r and multiply it by 6r to get -30r^2 and multiply -5r times -10 to get 50r
now the equation looks like this:
8r^2 + 16r - 30rsquared + 50r
now look for anything that you can reduce. because 8r and 30r are both squared you can subtract those two to get - 22r^2. then look at the 16 and the 50, they both have r's so you can add those two to get 66r
so the simplified problem is
-22r^2 + 66r

Answer 3

2r(4r + 8) - 5r(6r - 10)
8r^2 + 16r - 30r^2 + 50r
(8 - 30)r^2 + (16 + 50)r
-22r^2 + 66r

ANS : A.

Answer 4

( 2r * 4r) + (2r * 8) - (5r * 6r) + (5r *10)

=( 8r^2 ) + ( 16r ) _ (30r^2) +(50r)

= -22r^2 + 66r

Answer 5

2r(4r+8)-5r(6r-10)
=8r^2+16r-30r^2+50r
=-22r^2+66r

Answer 6

8r^2+16r-30r^2+50r
=-22r^2+66r

Answer 7

opening the brackets: open and simplify but remember [ (+)*(-)= (-); and (-)*(-)=(+); (+)*(+)=(+) ]
8r^2+16r-30r^2+50r
-22r^2+66r (ans)
therefore answer is (a)

Answer 8

22r - 2
or 4r
or 22r - 20 r

Answer 9

8r^2+16r-30r^2+50r
-22r^2+66r
A

Answer 10

A. 44r^2
B. 88r^2
C. -3r^2
D. 28r^2