Solve thw system of equation: 2x+y=18, 2x+3y=42

(3,12)

Step-by-step explanation:

2x+y=18 equn. (1)

2x+3y=42equn.(2)

to eliminate x, subtract equn.(2) from equn.(1)

0-2y=-24

divide via by -2

-2y/-2=-24/-2

y=12

to solve for x, put y in any equation.

from equn. (1) 2x+y=18

2x+12=18

subtract 12 from both sides

2x=6

divide via by 2

2x/2=6/2

x=3

(3,12)

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this