Answer:
Step-by-step explanation:
Silicon is a member of Group 14 (IVA) in the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Silicon is also part of the the carbon family. Other carbon family elements include carbon, germanium, tin, and lead. Silicon is a metalloid, one of only a very few elements that have characteristics of both metals and non-metals.
Silicon is the second most abundant element in the Earth's crust, exceeded only by oxygen. Many rocks and minerals contain silicon. Examples include sand, quartz, clays, flint, amethyst, opal, mica, feldspar, garnet, tourmaline, asbestos, talc, zircon, emerald, and aquamarine. Silicon never occurs as a free element. It is always combined with one or more other elements as a compound.By the early 1800s, silicon was recognized as an element. But chemists had serious problems preparing pure silicon because it bonds (attaches) tightly to oxygen. It took chemists many years to find out how to separate silicon from oxygen. That task was finally accomplished in 1823 by Swedish chemist Jons Jakob Berzelius (1779-1848).
Silicon's most important application is in electronic equipment. Silicon is one of the best materials from which to make transistors and computer chips. The total weight of silicon used for this purpose is relatively small. Much larger amounts are used, for example, to make metal alloys. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals.
Answer:
large = 18 3/4 = 18.75
small = 13/2 = 6 1/2 = 6.5
Step-by-step explanation:
Let l = the weight of large boxes
s = weight of small boxes
2 large and 3 small weights 57
2l+3s = 57
6 large and 5 small wights 145
6l+5s = 145
Multiply the first equation by 3
3(2l+3s) = 57*3
6l +9s =171
Subtract the second equation
6l +9s =171
-6l -5s = -145
-----------------------
4s =26
Divide each side by 4
4s/4 = 26/4
s = 26/4 = 13/2
Substitute this into the first equation
2l +3s = 57
2l + 3(13/2) =57
Multiply by 2 to get rid of the fractions
2(2l + 3(13/2)) =57*2
4l + 39 = 114
Subtract 39 from each side
4l +39-39 = 114-39
4l =75
Divide by 4
4l/4 = 75/4
l = 75/4 = 18 3/4
For 3x + 12 + x, do like terms:
4x + 12
For 4(3 + x), multiply
12 + 4x
They are both the same, just written in different ways. One is adding like terms and the other is multiplying with parentheses. Even though it may be switched around, it is still the same.
Hope this helps :)
