Lucia finds that open paren 3 x squared plus 3 x plus 5 close paren plus open paren 7 x squared minus 9 x plus 8 close paren is equal to 10 x squared minus 12 x plus 13 What error did Lucia make?
Answer
A
She combined the terms 3 x and negative 9 x incorrectly.
B
She did not combine all like terms.
C
She found the difference instead of the sum.
D
She combined the terms 3 x squared and 7 x squared incorrectly.
Explanation
Add like terms: 3x² + 7x² = 10x², 5 + 8 = 13, and 3x − 9x = −6x. Lucia’s middle term should be −6x, not −12x, so she combined 3x and −9x incorrectly.
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