Estimate the following sum by clustering. 14.2 + 15.51 + 14.99 + 15.8

Below

Step-by-step explanation:

Notice that:

● 14.2 = 14+0.2

● 15.8 = 15 +0.8

● 0.8+0.2 = 1

So:

● 14.2 +15.8 = 14+15 +0.2+0.8

● 14.2+15.8 = 14+1+15 = 15+15 = 30 (1)

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Notice that:

● 14.99 = 14+0.99

● 15.51 = 15+0.50+0.01

● 0.99 + 0.1 = 1

● 14.99+15.51 = 14+0.99+0.5+0.01

● 14.99+15.51= 14 + 1 +0.5

● 14.99+15.51 = 15+0.5 (2)

●(1)+(2) = 30 +15+0.5 = 45+0.5

So the total sum is 45.5 (45+0.5)

60

Step-by-step explanation:

14.2 + 15.51 + 14.99 + 15.8

= 14.2 + 15.8 + 15.51 + 14.99

= 30 + about 30.5

= 60.

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!