已知25a2-10a+1+|4b+1|=0,求[(4a+3b)(4a-3b)-(2a-5b)(8a+5b)]÷(-2b).
问题描述:
已知25a2-10a+1+|4b+1|=0,求[(4a+3b)(4a-3b)-(2a-5b)(8a+5b)]÷(-2b).
答
∵25a2-10a+1+|4b+1|=0,∴(5a-1)2+|4b+1|=0,∴a=15、b=−14∴[(4a+3b)(4a-3b)-(2a-5b)(8a+5b)]÷(-2b)=(16a2-9b2-16a2+25b2+30ab)÷(-2b)=(16b2+30ab)÷(-2b)=-8b-15a=-8×(-14)-15×15=2-3...