5a + 2b = -16
a + 3b = 15
a= -6 b= 7 so, i ahve the answer I just need help in the steps in finding the answer.
2007-04-23 11:00:11 · 3 answers · asked by grem 3 in Science & Mathematics ➔ Mathematics
You need to cancel out either a or b.
So what i would do is multiply the 2nd equation by -5
-5(a +3b) = -5(15)
your new second equation will be
-5a -15b = -75
then solve the 2 equations with 2 unknowns.
5a+2b=-16
-5a-15b=-75
which give -13b=-91
b= 7
then plug b back into one of the equations to find a
2007-04-23 11:07:05 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Multiply the second eq by 5 to get 5a + 15b = 75.
Now subtract it term by term from the first: the 5a's cancel leaving
-13*b = -75-16
b = 91/13 = 7
put the value of b in either eq (like the second one)
a + 21 = 15
a = -6
2007-04-23 18:10:41 · answer #2 · answered by gp4rts 7 · 1⤊ 0⤋
5a + 2b = -16
a + 3b = 15 Multiply this eqn by 5
5a + 15 b = 75 Subtract this from first eqn
5a + 2b = -16
-5a - 15b = -75
-13b = -91
b = 7
a + 3(7) = 15
a + 21 = 15
a = -6
2007-04-23 18:10:14 · answer #3 · answered by kale_ewart 5 · 1⤊ 0⤋