Let a and B be rational numbers, | A-3 | + | B + 7 | = 0. Find the value of (a + b) [- A - (- b)]

Let a and B be rational numbers, | A-3 | + | B + 7 | = 0. Find the value of (a + b) [- A - (- b)]

Because:
|a-3|+|b+7|=0
|a-3|≥0,|b+7|≥0
therefore
a-3=0,b+7=0
a=3,b=-7
（a+b)[-a-(-b)]=(b+a)(b-a)=(-7+3)(-7-3)=40

Given rational numbers a and B, and (a + √ 3b) ^ 2 = 3 + A ^ 2-A √ 3, find the value of √ a + B

Left a & # 178; + 2A √ (3b) + 3B = 3 + A & # 178; - a √ 3
So a-178; + 3B = 3 + a-178;
And 2A √ (3b) = a √ 3
So B = 1
a=0
So the original formula is 1

Given that a and B are rational numbers, and the square of (a + √ 3 × b) is 7-4 √ 3, find the value of a and B

(a + √ 3 × b) ^ 2 = a ^ 2 + 2 √ 3AB + 3B ^ 2 = 7-4 √ 3 has: A ^ 2 + 3B ^ 2 = 7, ab = 7 let B = 2 / A, substitute a ^ 2 + 3B ^ 2 = 7 to get: A ^ 2 + 12 / A ^ 2 = 7a ^ 4-7a ^ 2 + 12 = 0 solution: A ^ 2 = 3, a ^ 2 = 4 because a and B are rational numbers, so a = 2 or - 2, so the value of a and B is a = 2, B = - 1 or a = - 2, B = 1