Multiplying certain list elements by certain numbers

Question

I have the list:

List1={{7, -0.9}, {10,-1}, {12, -2}, {15, -2}}

Would like to receive the next list:

List2={{7, -0.9*2*List1[[1]][[1]]}, {10,-1*2*List1[[2]][[1]]}, {12, -2*2*List1[[3]][[1]]}, {15, -2*2*List1[[4]][[1]]}}

Those multiply all second elements of the list by 2, and then by the corresponding first element How can this be done?

Answer 1

List1 /. {f_, l_} :> {f, 2*l*f}

Answer 2

MapApply[{#1, 2 #1 #2}&]@List1

(* {{7, -12.6}, {10, -20}, {12, -48}, {15, -60}} *)

Or

{#[[All,1]], 2 #[[All,1]] #[[All,2]]}&@List1//Transpose

Answer 3

list = {{7, -0.9}, {10, -1}, {12, -2}, {15, -2}};

A variant of 1066's answer

{#, 2 ##} & @@@ list

{{7, -12.6}, {10, -20}, {12, -48}, {15, -60}}

Using Cases

Cases[list, {a_, b_} :> {a, 2 a b}]

{{7, -12.6}, {10, -20}, {12, -48}, {15, -60}}