Question

subtract
a) subtract 8xy+3xy+21 from 6xy+9yz+17
b) subtract a³+b³+³-3abc from 7abc-3a³+5b³-c³​

Answer 1

Answer:

$1) \: 6xy + 9yz + 17 - (8xy + 3xy + 21) \\ \\ = 6xy + 9yz + 17 - 8xy - 3xy - 21 \\ \\ = 6xy - 8xy - 3xy + 9yz + 17 - 21 \\ \\ = - 5xy + 9yz - 4$

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$</strong><strong>2</strong><strong>)</strong><strong>\</strong><strong>:</strong><strong>7abc - 3 {a}^{3} + 5 {b}^{3} - {c}^{3} - ( {a}^{3} + {b}^{3} + {c}^{3} - 3abc) \\ \\ = 7abc - 3 {a}^{3} + 5 {b}^{3} - {c}^{3} - {a}^{3} - {b}^{3} - {c}^{3} + 3abc \\ \\ = - 3 {a}^{3} - {a}^{3} + 5 {b}^{3} - {b}^{3} - {c}^{3} - {c}^{3} + 7abc + 3abc \\ \\ = - 4 {a}^{3} + 4 {b}^{3} - 2 {c}^{3} + 10abc \\ \\ = - 2(2 {a}^{3} - 2 {b}^{3} + {c}^{3} - 5abc) \\ \\ = 2 {a}^{3} - 2 {b}^{3} + {c}^{3} - 5abc$

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Answer 2

Answer:

77778+787889+78888/677888

=687+6778+67/99