So I'm not looking for the answer I already know from looking in the book but I'm confused because it doesn't really explain where the r+3 and 8 came from? Can you please explain this to me in easy terms ..not so good at math. Thank you! Happy Easter.
7r^2 + 13r=24
7r^2 + 13r-24=0
7r(r+3) -8(r+3)=0
(r+3)(7r-8)
Answer -3, 8/7
7r^2 + 13r=24
7r^2 + 13r-24=0
7r(r+3) -8(r+3)=0
(r+3)(7r-8)
Answer -3, 8/7
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It's just factoring by grouping.
7r^2 + 13r=24
is the same as
7r^2 + 21r - 8r -24 = 0
Then, you can factor (r + 3) out of (7r^2 + 21r) and out of (-8r - 24) to get:
7r(r+3) - 8(r+3) = 0
That's where the -8 and (r+3) came from. Please give me points! I need them!
7r^2 + 13r=24
is the same as
7r^2 + 21r - 8r -24 = 0
Then, you can factor (r + 3) out of (7r^2 + 21r) and out of (-8r - 24) to get:
7r(r+3) - 8(r+3) = 0
That's where the -8 and (r+3) came from. Please give me points! I need them!
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Now complete the exercise:
(r+3)(7r-8) = 0, so r + 3 = 0 or 7r - 8 = 0
Therefore, r = -3 or r = 8/7
Your factoring is insightful, but this process does not always work. However, the quadratic formula does.
(r+3)(7r-8) = 0, so r + 3 = 0 or 7r - 8 = 0
Therefore, r = -3 or r = 8/7
Your factoring is insightful, but this process does not always work. However, the quadratic formula does.
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I would have done it differently
Rearrange
7r^2 + 13r = 24
7r^2 + 13r - 24 = 0
factorise
(7r - 8)(r + 3)
r = 8/7 and r = - 3
Rearrange
7r^2 + 13r = 24
7r^2 + 13r - 24 = 0
factorise
(7r - 8)(r + 3)
r = 8/7 and r = - 3
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That's good u know the answer