what is 4n+3 (in sequences and terms)

 $$\small{\text{Arithmetical sequence : } }\boxed{\ a_n=a_1+(n-1)*d\ } \\\\
a_1=7 \text{ and } d = 4 \text{ , so we have } a_n = 7 + (n-1) * 4 = 3+4n \\
7+0*4,\ 7+1*4,\ 7+2*4,\ 7+3*4, \ +\dots+,\ 7+n*4$$

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To solve your question you would need to know what the value of n is.

If n=3 then your equation would be 4(3)+3, which equals 15.

If n=2 then your equation would be 4(2)+3, which equals 11.

If n=8 then your equation would be 4(8)+3, which equals 35.

Your equation will still only be 4(n)+3 until you find the value of n, an when you find out what the value of n is you replace n with that value. I hope that this helps.

f(n)=4n+3

n          1      2      3      4

f(n)     7      11   15    19       etc