I have solved this question but now I am supposted to check my answer. I do not fully understand how to do it so if anyone can help me out here you will be doing me a great service. Thanks in advance
7(3x+4)=8(2x+5)+13
21x+28=16x+40+13
21x-16x=40+13-28
5x=25
x=5
2007-06-26 06:55:24 · 5 answers · asked by trevor s 2 in Science & Mathematics ➔ Mathematics
Plug 5 back in for x in the original equation and make sure it resolves to n = n:
7(3(5) + 4) = 8(2(5) + 5) + 13
7(15 + 4) = 8(10 + 5) + 13
7(19) = 8(15) + 13
133 = 120 + 13
133 = 133
2007-06-26 06:58:58 · answer #1 · answered by Dave 6 · 0⤊ 0⤋
To check your answer insert x=5 into every x
7(3*5+4) = 8(2*5+5) +13
7(15+4) = 8(10+5) +13
7(19) = 8(15) +13
133 = 120 + 13
133 = 133
Since the two sides of the equation equals each other the answer is correct.
2007-06-26 14:01:35 · answer #2 · answered by im21ders 2 · 0⤊ 0⤋
substitute in the x=5 into the first equation and verify that both sides of the eqn are equivalent
7(3*5+4) = 7(15+4) = 7*19 = 133
8(2*5 + 5) + 13 = 8(10+5) + 13 = 8*15 + 13 = 120+13 = 133
that's how you check your answer
2007-06-26 14:00:27 · answer #3 · answered by Navidad_98 2 · 0⤊ 0⤋
Backtrack to the top, and substitute 5 for x. You should get an identity (133=133)
2007-06-26 14:00:15 · answer #4 · answered by cattbarf 7 · 0⤊ 0⤋
to check simply put 5 back in to your original equation to make sure both sides equal each other.
2007-06-26 13:58:07 · answer #5 · answered by miggitymaggz 5 · 0⤊ 0⤋