更新時(shí)間:2024-01-12 12:54:51作者:貝語網(wǎng)校
已知一個(gè)多項(xiàng)式與3x2+9x的和等于3x2+4x-1,則此多項(xiàng)式是
A.-6x2-5x-1
B.-5x-1
C.-6x2+5x+1
D.-5x+1
B
本題涉及多項(xiàng)式的加減運(yùn)算,解答時(shí)根據(jù)各個(gè)量之間的關(guān)系作出回答.
解答:解:設(shè)這個(gè)多項(xiàng)式為M,
則M=3x2+4x-1-(3x2+9x)
=3x2+4x-1-3x2-9x
=-5x-1.
故選B.
點(diǎn)評:解決此類題目的關(guān)鍵是熟練運(yùn)用多項(xiàng)式的加減運(yùn)算、去括號法則.括號前添負(fù)號,括號里的各項(xiàng)要變號.