Why did Meselson and Stahl choose to grow E. coli in broths of nitrogen isotopes? A. The bacteria's phosphate groups would be replaced by the nitrogen.
B. The nitrogen would be incorporated into deoxyribose.
C. The nitrogen would influence bonding between base pairs.
D. The nitrogen would be incorporated into the DNA nucleotides

i thinking chemical change

answer-

the statement that f(x) = |x+a| + b has exactly one x-intercept is sometimes correct.

solution-

it solely depends on b, whether the function will have one or two or zero x intercept.

this plot of the given function, f(x) = |x+a| + b will be the basic absolute value graph i.e v shape, with vertex translated to (-a, b), instead of origin.

1-   if b is zero, the graph will have exactly one x-intercept, at x= -a

2- if b is positive, the whole graph will be above the x-axis, hence it will have no x-intercepts.

3- if b is negative, the graph will be below the x-axis, hence it will have two x-intercepts.

∴ the statement is sometimes true.