Answer
$y=2x+4 $
Work Step by Step
1. The tangent line at x=a passes through the point (a, f(a))$\\$
(we must first find f(a)$\\$
2. It has slope m$=f^{\prime}(a)\\$
3. Its equation (point slope): $y-f(a)=f^{\prime}(a)(x-a)\\$
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(The tangent to a line is the line itself)
Nevertheless, here is the calculation:
1. $x=-1, \ \ \ f(-1)$=$2(-1)+4=2.\\$
The point on the graph is $(-1,2).\\$
2. Slope. $\\$
$f^{\prime}(x)=$ (sum, constant times x, constant rules)$ = 2+0=2\\$
$m=f^{\prime}(-1)=2\\$
3. Equation.
P $(-1,2),\ m=2 \\$
$y-2=2(x-(-1)) \\$
$y-2=2x+2 \\$
$y=2x+4 $
image enclosed: graph